Alexander Medvedev was in a relaxed mood as he settled into the sumptuous sofa in the quiet reception room of the Mandarin Oriental hotel next to London's Hyde Park.

A day before he had held tough talks with Shell about alarming cost-overruns on the Sakhalin 2 project in eastern Russia. But on Saturday he was less tense as he looked forward to his main job while in London: representing his employer at celebrations for the Russian New Year in Trafalgar Square.

A tall, polite but straight-speaking man, Mr Medvedev is deputy chairman of the management committee at Gazprom and general director of Gazexport, the overseas gas sales arm.

His good English - compared with the group chairman, Alexei Miller - make him the main mouthpiece in the non-Russian-speaking world, although in the past this would have been deemed unnecessary.

Following the recent clash over gas supplies between Russia and Ukraine, however, and the subsequent bad publicity, Mr Medvedev is suddenly more than happy to talk and - as he sees it - set the record straight.

It is particularly important to do so in Britain where Gazprom has recently opened a new office and has big plans to expand, yet criticism of the Ukraine situation was particularly harsh.

"We are now facing the necessity to explain what happened and we will not economise on the time needed to do so. But I believe we should not exaggerate the damage raised by this issue. The flow of gas [to western Europe] was not halted," he argues.

Gazprom, which controls a quarter of world gas reserves and recently boasted that it would soon be bigger than BP or Shell, has delivered uninterrupted supplies to Europe for the past 30 years, despite all kinds of currency and other economic crises, he points out.

But what has shocked many in the west is Vladimir Putin's involvement in this spat. He appeared to be using gas exports to score political points against Ukraine for its "Orange revolution", which moved it away from Moscow's orbit and towards Nato and the west.

Mr Medvedev says Mr Putin's involvement was inevitable. "I believe that Russia is still in transition and that's why the role of president is not only to develop the appropriate structure for market reform and social programmes but inevitably he should be involved in the development of such a company as Gazprom," he argues, pointing out that the state still owns 50% plus one share.

But he said it was still a surprise - "a big surprise" - that Mr Putin tried to break the commercial deadlock between Gazprom and its Ukrainian counterpart over a new supply contract by offering a loan to help pay for the fourfold increase in prices.

This was done not to punish a potential enemy but to help an ally. "I believe he made that offer as part of his responsibility to retain friendly relations with Ukraine," argued Mr Medvedev.

He said no one should be surprised about a national leader taking a role given the "highly political nature of all major energy deals".

He added: "It is too naive to say that the energy business can be completely separated from foreign policy. Politics is always there, maybe not directly but indirectly.

"But we as Gazprom acted in this as a commercial organisation. If Russia wanted to use gas as a political weapon then surely it would have used it after the [Orange] revolution period.

"We started negotiating with Ukraine about 2006 gas deliveries in March 2005 and used European rules as initiated by Ukraine. In the absence of such agreement on January 1 we had to stop deliveries," Mr Medvedev said.

The problem was exacerbated by western politicians "taking all the terminology from the cold war times", he said, perhaps with reference to the former energy minister Brian Wilson.

The special adviser to Tony Blair had suggested in the Guardian that the row highlighted the danger of Britain relying too heavily on imported gas instead of using nuclear and other energy sources.

Gazprom is keen to reverse this line of thinking and says it wants to increase gas sales to Britain from 4bn cubic metres a year now to 10bn by 2010.

The new north European pipeline could help towards this target and Gazprom has talked with UK firms such as Centrica about new import volumes.

"We now have a good wholesale business in the UK with big industrial customers and power stations. We are aiming to secure 20% of the market by 2015," he explained.

It could achieve its UK aims sooner by buying a major utility. This could even include a business supplying energy direct to the consumer, something Gazprom has so far avoided. Scottish Power, which last year held takeover talks with Germany's E.ON and is worth about £11bn, would be one option.

"We are looking at such opportunities now. We are not afraid of such size as Scottish Power but we have no concrete plans at this moment," Mr Medvedev said.

Another option would be buying a major oil company in Britain or elsewhere, to complement the acquisition of its Russian rival Sibneft, which first gave Gazprom a substantial oil business.

Gazprom is also trying to get closer to western shareholders. The Russian government still owns half of the company but the Kremlin last week gave the green light to foreign investors buying as much as 29% of the firm.

The company celebrated as its shares soared 17% in Moscow on the back of this.

The festivities in Trafalgar Square last weekend were also lavish. Mr Medvedev no doubt hopes that in future Gazprom consumers will join expats to rejoice in all things Russian.

Profile: Alexander Medvedev

Alexander Medvedev, deputy chairman of Gazprom, is relatively new to the company but he is playing a critical role in its ambitious plans to become a global leader in both the oil and gas sectors.

The 51-year-old was born in Shakhtersk, in the Sakhalin region, and graduated from the Moscow Physical and Technical Institute in 1978 with a doctorate in economics. He went on to work in the global economy and foreign relations institute at the USSR Academy of Sciences.

Mr Medvedev later joined the Soviet Donau-Bank and became managing director of its Inter Trade Consult subsidiary. He moved on to become a director of the Austrian IMAG Investment Management & Advisory Group before being appointed in 1997 as vice-president of the Eastern Oil Company in Russia.

He was at the company when it was taken over by the now-troubled Yukos but left soon afterwards with bitter words to say about the way the business was being run by the founder of Yukos, the now-jailed Mikhail Khodorkovsky.

In 2002 he was hired by the former deputy energy minister Alexei Miller to become his deputy at Gazprom, which remains the world's largest gas company.

Accessible, down-to-earth, with good English and unafraid to speak his mind, Mr Medvedev has been charged with overseeing export policy and foreign relations.