BRASILIA, Sept. 14 (Xinhuanet) -- Leaders of Brazilian political parties, from both the ruling government and the opposition, demanded on Wednesday Congress lower house speaker Severino Cavalcanti resign under a corruption accusation.

    Cavalcanti, 74, from the moderate Progressive Party, an ally ofthe government's Workers Party, has been accused of extortion linked to a small restaurant in the parliament building. He denied taking any money and said he will not step down from his post.

    A businessman presented police with a copy of a check on Wednesday, saying it was proof of bribes taken by Cavalcanti.

    The businessman, Sebastiao Buani, said the check for 7,700 reals (3,200 US dollars) was part of the 111,000 reals (47,800 dollars) that he paid Cavalcanti between 2002 and 2003 in exchange for the privilege of running a restaurant inside the Congress house.

    "Here is the check," Buani said, holding a copy of the canceled check at a press conference at federal police headquarters. Buani said he paid the bribe because he needed the restaurant concession to support his six children.

    Police could not immediately confirm the authenticity of the check allegedly cashed by the Cavalanti's personal secretary in July 2002.

    Five political parties and a dissident group of the ruling Workers Party asked the House Ethics Committee to start an investigation into the "violation of parliamentary decorum" which could lead to Cavalcanti's removal.

    The head of the committee, Ricardo Izar, said he would open an investigation.

    "The appearance of a material evidence fully alters the situation. Deputy Cavalcanti has to resign to the Presidency (of Congress) and respond to the investigation process," said the Workers Party leader in the Chamber of Deputies, Henrique Fontana,after a conversation with the party president Tarso Genro.

    On Wednesday the leader of the opposition Liberal Front Party, Rodrigo Maia, said the check being cashed by Cavalcanti's secretary is very serious.

    "The denunciation was confirmed. It is for him to take an immediate position. The situation is grave, so I don't think he isin any condition to preside at today's session," said Maia.

    In response, Cavalcanti Wednesday decided not to preside at the session to vote whether or not to expel house representative Roberto Jefferson, who is accused of accepting money in illegal campaign funds from the Workers Party. Enditem