The Transport Minister Shane Ross has accused the Green Party leader Eamon Ryan of being on pills to help him forget his own time in government.
Mr Ross said Mr Ryan must be "smoking amnesiacs" to be able to lecture the Dáil on planning issues.
He criticised the Green Party leader for propping up the Fianna Fáil governments of Bertie Ahern and Brian Cowen.
After a row broke out in the Dáil over funding for transport, Minister Ross rounded on the Green Party leader.
He said: "I just wish to know what pills this man is taking. This man must be smoking amnesiac.
"There's a thing called an amnesiac pill and it makes you forget. This man, for his years in the wilderness, he took these amnesiac pills, he's forgotten he was in government when the country was bankrupt.
"He's forgotten about the four-year plan to achieve reform, his plan went up in smoke. Why? Because he spent money like there was no tomorrow."