Russia may offer Ukraine a loan of between $5 billion and $6 billion for construction of the third and fourth units of the Khmelnitsky nuclear power plant, Russian Prime Minster Vladimir Putin said on Saturday.

Putin was speaking after talks in Moscow with his Ukrainian counterpart Mykola Azarov. The meeting also involved Gazprom head Alexei Miller and Deputy Prime Minister Igor Sechin.

"We discussed cooperation in the nuclear energy sphere and the possibility of financing work on the third and fourth units of the nuclear plant by the Russian side to the volume of $5-6 billion," Putin told journalists.

He also said that Azarov had passed on "interesting" proposals by Ukrainian President Viktor Yanukovych in the gas sphere.

Yanukovych, who was inaugurated in February, is seeking to revise the long-term gas deal signed by then prime minister Yulia Tymoshenko and Putin in early 2009, which increased the price Ukraine paid for Russian gas, further straining the country's troubled finances.

In return for cheaper gas, Ukraine could offer Russia a stake in its gas transportation system, which currently carries about 80% of Russian natural gas exports to Europe, and a discount for Russian gas transit to European consumers.

Putin added that the proposals would need careful consideration.

"We have made a whole range of proposals to the Russian side - they are complex and require detailed study," Azarov said, adding that he hoped the issue could be resolved in the near future.

Azarov also said that Putin had promised to give instruction for the resumption of duty-free supplies of Ukrainian pipes to Russia.

Russia halted from April 1 the imports of Ukrainian steel pipes duty free over the failure of the two ex-Soviet republics to agree on a quota for the second quarter of 2010.