Guatemalan prosecutors have launched an investigation into a presidential candidate, six lawmakers and a cabinet minister on suspicion of corruption, the U.N.-backed International Commission Against Impunity in Guatemala (CICIG) said late on Monday.

The Guatemalan attorney general's office and the CICIG said in a joint statement the eight had overseen the approval and distribution of bribes worth $7.5 million for 62 deputies between 2012-2015 during the administration of former President Otto Perez.

Perez and his former vice president Roxana Baldetti are in prison and are being tried on various corruption charges. Both, who are members of the conservative Patriot Party, deny any wrongdoing.

According to the CICIG, bribes were distributed from Baldetti's office to trusted Patriot Party deputies and were used to secure approval of certain laws and judicial appointments.

All eight people under investigation belonged to the Patriot Party in the last administration.

Estuardo Galdamez is now seeking to succeed President Jimmy Morales as president of Guatemala, representing Morales' conservative National Convergence Front (FCN). Guatemala holds a general election in June.

Galdamez on Tuesday posted a statement on Twitter from the FCN rejecting the accusations.

The CICIG and the attorney general's office said they are also investigating Economy Minister Acisclo Valladares in the case.

Valladares told Reuters the allegations against him were groundless and that the probe was based on unreliable witnesses.

The lawmakers accused by the CICIG could either not be reached for comment or rejected the allegations in local media.

CICIG investigations led to the downfall of Perez in 2015 and the anti-graft body also went after Morales, alleging he broke campaign finance rules during his presidential run. But it failed to secure enough votes in Congress to impeach him.

Morales accused the CICIG of abusing its power and refused to renew its mandate, which will end in September.

Last month, another presidential candidate was arrested in the United States, accused of making deals with the Sinaloa drug cartel in Mexico.