Irish Prime Minister Brian Cowen has brushed aside speculation that he was drunk or hungover when he went on a morning radio show following a late night with parliamentary colleagues at their annual conference.

Cowen's hoarse performance during an interview on the state broadcaster prompted a flurry of comment on Twitter, including a broadside from one opposition politician that he sounded "halfway between drunk and hungover".

Asked whether he was still feeling the effects of the night before Cowen told reporters: "Absolutely not, that's ridiculous."

Party officials said he suffered from nasal congestion.

But the negative internet comment overshadowed the second day of a meeting designed to shore up support for a prime minister whose popularity ratings are on the floor and whose parliamentary majority is wafer-thin.

Renowned for his gruff public persona, Cowen traditionally lets his hair down at the annual conference with sing songs and pints of beer. On Monday night he regaled reporters and colleagues with a skit in the conference venue's bar.

He has previously denied that he has a drink problem.