GUATEMALA CITY (Reuters) - Guatemala s attorney general and a U.N. anti-graft body accused the mayor of Guatemala City, Alvaro Arzu, of corruption on Thursday, adding him to a long list of influential politicians under investigation for suspected wrongdoing. Arzu, who was also Guatemalan president from 1996-2000, rejected the accusations after they were announced by Ivan Velasquez, head of the International Commission Against Impunity in Guatemala (CICIG), and Attorney General Thelma Aldana. Velasquez, who has unsuccessfully tried to impeach President Jimmy Morales but was instrumental in bringing down his predecessor Otto Perez, said Arzu was suspected of creating fake payrolls and using public funds for his re-election bid in 2015.  It was possible to document existence of bogus positions in the Guatemala municipality,  Velasquez, a veteran Colombian prosecutor, told a news conference that Arzu also attended. Velasquez said the positions were created for relatives of Byron Lima, a former security official for Arzu and army captain who died in a prison riot in 2016 while serving a 20-year sentence for the murder of Bishop Juan Gerardi in 1998. Velasquez and Aldana, who worked together to bring charges against the now-imprisoned Perez, need Supreme Court approval to strip Arzu of the immunity he enjoys as an elected official. Arzu, one of the most influential politicians in Guatemala and mayor of the capital since 2004, tried to get hold of the microphone to face down his accusers during the news conference.  This pair are trying to get back at me because they couldn t carry out their  coup  with another president,  Arzu told reporters.  These were not bogus positions, those people came to work every day. They should go ahead and investigate me, I m not bothered (that they are trying to strip my immunity),  he said. Arzu has been a vigorous supporter of President Morales who, unlike Perez, managed to avoid being stripped of his immunity by Congress when it was put to a vote last month. That followed CICIG accusations that Morales used illicit campaign financing during his run for the presidency in 2015. Velasquez and Aldana have also accused Guatemala s main political parties of engaging in illegal campaign financing, setting much of the establishment against them. Former president Perez and his ex-vice-president are in prison and on trial for corruption. Many senior officials from his Cabinet are also under investigation for suspected graft. 