KIEV, May 12 - Naftogaz Ukrayiny, the national oil and gas company, has been struggling to meet its debt payment obligations, increasing the chance of default this year, the country’s financial watchdog warned on Tuesday.

Naftogaz is due to repay 17.5 billion hryvnias, or about $2.2 billion, in debt in 2009, which is more than a half of the company’s capital, the Accounting Chamber, the country’s independent financial watchdog, said.