By Oleg Shchedrov

HANOI, Nov 20 (Reuters) President Vladimir Putin moved from diplomacy to promoting Russian economic interests in Vietnam, which used to be a major Moscow ally, and held out the prospect today of billions of dollars in investment.

Putin, who took part in the Asia Pacific Economic Cooperation (APEC) summit in Hanoi last week, met Vietnamese President Nguyen Minh Triet, Prime Minister Nguyen Tan Dung and Communist Party leader Nong Duc Manh.

In a ceremony recalling the days when the Soviet Union armed North Vietnam to fight the United States and helped reconstruct the country after the war, Putin and Triet gave awards to Russian and Vietnamese employees of joint oil venture Vietsovpetro.

Russian and Vietnamese Orders of Friendship handed out to company executives and workers in the presidential palace were clearly intended to show bilateral ties have gained some of the warmth lost in the first post-Soviet decade.

''We have fulfilled the task of expanding our trade and economic relations,'' Putin, who first visited Vietnam in 2001 to end a lull in relations, told a news conference. ''Their volume has grown three-fold.'' Trade turnover between Russia and Vietnam stands at about $1 billion a year.

Putin and Triet signed a declaration, committing themselves to extending the existence of Vietsovpetro beyond 2010 when an agreement expires.

A spokesman for Russia's giant Gazprom, which is exploring an offshore field south of Hanoi, told reporters the company could also take part in delivering gas to clients in Vietnam.

''We are signing today an agreement with the Vietnamese company Petrovietnam to expand our cooperation, including the examination of possibilities to create in Vietnam a gas infrastructure, which is now in an embryonic state,'' Sergei Kupriyanov said.

''Russian companies are already taking part in upgrading and building new energy sites,'' Putin said. ''We are ready to consider further cooperation, including in nuclear energy.'' To facilitate growing trade, Russia's Vneshtorgbank and Vietnam's third-largest Bank for Investment and Development opened a $10-million joint venture bank on Sunday.

Putin said Russia was specifically interested in expanding cooperation to the high-tech, machine-building, telecoms and space sectors.

''If these plans are successful, then we can speak about Russian investment in Vietnam worth billions of dollars,'' he said.

REUTERS AB HT1717