An international human rights group says Guatemalan courts are foot- dragging on high-profile cases and threatening the work of the country's prosecutors and a U.N. anti-corruption commission.

Human Rights Watch analyzed eight major cases that have bogged down and concluded the courts are undermining the anticorruption work by taking too long to process appeals and pretrial motions. In a report released Sunday, the group accuses the courts of trying to run out the clock on prosecutions by keeping defendants from ever making it to trial.

Among the cases is a customs fraud scandal that allegedly sent kickbacks to then President Otto Perez Molina and Vice President Roxana Baldetti. They resigned and were jailed to await trial, but more than 100 defense filings have delayed the trial.

Perez Molina and Baldetti, who resigned in 2015, both deny the charges against them.

Daniel Wilkinson, managing director of the Americas division at Human Rights Watch, said Guatemala has made progress on holding officials accountable for abuses of power, but still needs to "move forward and close those circles with trials." "The strategic defense (of those accused) was always to delay the cases," Wilkinson said.

The report notes a pattern in which pretrial proceedings drag on as defense lawyers appeal court decisions and file petitions seeking the recusal of judges.

"The repeated filing of such petitions has brought many key prosecutions to a standstill, and lawyers are not effectively sanctioned even when filing petitions that are manifestly frivolous," Wilkinson said.