KIEV, May 14 - Naftogaz Ukrayiny paid cash for only 32% of Russian gas imports in April, while the rest of the payment was a credit from Gazprom, a senior official at President Viktor Yushchenko said Thursday.

Naftogaz earlier reported it paid $620 million to Gazprom on May 6 to cover imports of 2.3 billion cubic meters of gas in April.

The revelation that only a fraction of the payment was made in cash bolsters concerns that Naftogaz may eventually fail on future payments that may trigger a fierce reaction from Gazprom.