Portugal's economy minister has resigned after making a rude gesture to an opposition lawmaker during a stormy debate in Parliament.

Manuel Pinho quit the center-left Socialist government late Thursday. Prime Minister Jose Socrates, who is preparing for a general election in September, said Pinho's gesture was "inexcusable."

Pinho placed a hand on each side of his head and stuck out his index fingers, imitating a bull's horns, while glaring at a Communist Party lawmaker seated nearby. In Portugal, the gesture means a man's wife is having an affair.

Pinho said he regretted his act during a tense state-of-the-nation debate, though he said he was responding to an insult from the lawmaker.

Pinho, who joined the government after the Socialist Party's landslide election victory in 2005, is credited with leading an effort to improve Portugal's development of new technology, especially in the renewable energy sector where Portugal has been among Europe's pioneers.

Finance Minister Fernando Teixeira dos Santos will also take over the role of economy minister starting Monday.