Malaysia's courts are to prosecute the country's best known opposition politician Anwar Ibrahim at a court appearance on Thursday and his lawyers said they expected him to be formally charged with sodomy. Anwar, who had hoped to win a parliamentary seat at a by-election set for Aug. 26, denies allegations he had sex with a male aide and says they are aimed at derailing his political comeback in which he has promised economic reforms. Police said in a statement issued on Wednesday that prosecutors had decided to prosecute Anwar for “carnal intercourse against the order of nature”. A 23-year man has said that Anwar, 60, had sex with him on several occasions, something which is illegal under Malaysia's sodomy laws and if found guilty Anwar could spend up to 20 years in jail, effectively ending his political ambitions. “This is a lie, the government's institutions are being used and clearly the decision was made under the personal directive of the prime minister,” Anwar told a press conference after the summons was issued. News of the court appearance came an hour after Malaysia's Election Commission set a date for a by-election in a parliamentary constituency held by Anwar's wife which he was expected to win easily. Anwar, who was barred from parliament in April 1999 after being convicted of corruption, plans to hold a confidence vote in the UMNO-led government in September in which he said he is confident he can win over 30 government MPs so as to win power. Anwar won the seat in which he will stand, Permatang Pauh seat in the northern state of Penang, in 1995 with a 20,000 majority when he stood as a government candidate. “At this moment, Anwar has the upper hand in the campaign as everyone expects him to win, but the Barisan (ruling coalition) strategy is to throw as much dirt as possible during the campaign so that even if he wins, he will win with some tainted allegations,” said James Chin, Professor of Political Science, Monash University Malaysia Campus. Anwar was imprisoned on corruption charges in April 1999, which meant he lost his parliamentary seat. He was released in 2004 and a bar on his standing for office expired in April. In elections in March, the opposition alliance deprived the government of its two-thirds majority due in part to popular anger over rising prices.