KIEV, Feb. 22 - Russian President Vladimir Putin, in a letter to his Ukrainian counterpart Viktor Yushchenko on Friday, urged Ukraine to clear its natural gas debt owed to Gazprom as soon as possible.

The letter, which focused on a number of issues involving the energy sector, comes after two weeks of intensive talks between top Russian and Ukrainian officials over the gas debts.

“The number one issue is the issue of timely payments for consumed natural gas,” Yushchenko said Friday citing the letter, according to a report posted by Yushchenko’s press service.

The letter underscores the importance the Russian authorities slap on the gas debt issue. Russian gas giant Gazprom last week threatened to cut gas supplies to Ukraine unless progress is made to clear the debt.

Ukrainian Prime Minister Yulia Tymoshenko, who spent two days in Moscow for gas talks earlier this week, said late Thursday that Ukraine would quickly pay $1 billion debt incurred in November and December 2007.

Naftogaz Ukrayiny, the national oil and gas company, paid a total of $284 million against the debt over the past eight days, making two installments, including $178 million on Wednesday and $106 million on February 14.

Gazprom has been earlier estimating the overall debt at $1.5 billion, which included $1 billion for gas supplied in 2007 and $500 million for gas supplied in January and February.

Yushchenko, who has been criticizing Tymoshenko for slow pace of debt payments, said Friday the government had enough money on its accounts to immediately pay the debt.

“If we are guided by national interests, then I don’t see any problem here,” Yushchenko said. “There is enough money to make the settlement.”

Yushchenko said he will hold a special meeting with Tymoshenko on Monday to get report on her latest talks in Moscow and on the progress in gas debt settlement.

The developments come as details emerge over new demands that Gazprom had made against Ukraine on Thursday in an on-going gas debt dispute.

Tymoshenko, who spent five hours in talks with Alexei Miller, the CEO of Gazprom, on Thursday, said that Gazprom, gad insisted that Ukraine must also return 4 billion cubic meters of gas in-kind.

The new demands mean that Ukraine will probably get 51 Bcm of gas in 2008, down from 55 billion cu m that had been originally expected, that may potentially create a shortage, analysts said.

The demands to return gas come on the top of $1.5 billion debt that Ukraine has been required to pay in cash, and put extra pressure on Ukraine to tap its strategic gas reserves for returning the gas.

In an address to a government meeting on Friday, Tymoshenko blamed RosUkrEnergo, a Swiss-based gas trader controlled by Gazprom, and its Ukrainian subsidiary UkrGaz-Energo for an unauthorized use of 4 Bcm last year that will now have to be returned to Gazprom.

“It appears that the gas traders have previously managed to use Central Asian gas that has been intended for 2008,” Tymoshenko told the meeting in comments aired by UT-1 television Friday.

“We don’t know whether they have exported this gas or what else have they done with it,” Tymoshenko said. (sb/ez)