Guatemalan President Otto Perez will be investigated for alleged corruption and Congress has been asked to consider lifting his immunity, the Supreme Court said Wednesday. The president has faced major protests calling for his resignation since a UN-backed investigation reported in April a customs bribery ring implicating a wide array of high-ranking officials.Last month the president fired three government ministers and his intelligence chief as he sought to get a grip on the widening scandal in the poor and violence-plagued Central American country.The probe against Perez, requested by an opposition party founded by Nobel peace laureate Rigoberta Menchu, was announced at a press conference by the chief justice of the Supreme Court, Josue Baquiax.The 13 members of the court studied a complaint from the Winaq party to the effect Perez knew about illegal transactions committed by senior officials involved in fraud in the customs and social security systems, Baquiax said. Now it is up to Congress to appoint an investigative commission, the chief justice said.The UN-backed probe, aimed at cleaning up the country's judicial system, concluded that senior customs officials took bribes from businessmen seeking to avoid paying taxes.In a separate scandal, the president of the Central Bank and the director of the Social Security system -- both of whom are close to Perez -- were arrested in May on charges of cheating the social security system out of $15 million. The president has resisted pressure to resign and to address the corruption allegations. But he has insisted he will serve out his full term, which ends in January next year.