Former Guatemalan President Alvaro Colom is escorted by police to a courtroom in Guatemala City, Tuesday, Feb. 13, 2018. Colom, who governed from 2008 to 2012, has been detained in a corruption case according to special prosecutor Juan Francisco Sandoval. (Luis Soto/Associated Press)

GUATEMALA CITY — Prosecutors in Guatemala said Tuesday they have detained former President Alvaro Colom and almost his entire former cabinet, including the current chairman of Oxfam International, in a corruption case involving a bus concession.

Colom, who governed from 2008 to 2012, is the latest in a series of former presidents to face legal problems. Colom was recently named by the Organization of American States as an envoy to Honduras, in a bid to help sort out disputed elections there.

Special prosecutor Juan Francisco Sandoval, who said Colom was arrested Tuesday, is looking into the questionable purchases of public buses for Guatemala City. Sandoval said those arrested face charges of fraud and embezzlement.

Sandoval said that the detentions included the ex-interior minister and the former ministers of finance, defense, economy, education, labor, environment, health and sports and culture. The former finance minister, Alberto Fuentes Knight, is the current chairman of Oxfam International.

The global nonprofit said in a statement that it did not know the nature of formal charges against Fuentes. “However, he has been entirely open with his Oxfam board and executive that he has been among former officials being investigated as part of a budgetary transaction made by the Guatemalan government while he was finance minister.

“He has assured us that he has cooperated fully with the investigation in the confidence he did not knowingly transgress rules or procedures,” the group added.

The case centers around a public bus company known as Transurbano. The government auctioned off 25-year concessions for Guatemala City bus routes and the private companies that won the contracts were later exempted from taxes.

Prosecutors say the process was deeply flawed and included subsidies and other measures that benefited public servants. The United Nations anti-corruption mission in Guatemala participated in the investigation.

A customs fraud scandal that allegedly sent kickbacks to then-President Otto Perez Molina and Vice President Roxana Baldetti led both to resign in 2015. They have been jailed awaiting trial, but more than 100 defense filings have delayed the trial.

Alfonso Portillo, Guatemala’s president from 2000 to 2004, was extradited to the United States and pleaded guilty to money laundering conspiracy in 2014.

He admitted accepting $2.5 million in bribes from the government of Taiwan to continue to recognize the Asian nation diplomatically.

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AP writer Danica Kirka in London contributed to this report.

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