A district administrator in northwestern Afghanistan has been accused of militant links and corruption, becoming the second senior Afghan official to be arrested in February.

The allegations come amid fears of infiltration and pressure on President Hamid Karzai to crack down on corruption.

The chief administrator in Bala Murghab, a heavily Taliban-influenced area, was detained late Thursday but officials did not disclose the news until Monday, after his interrogation.

Afghan President Hamid Karzai is under pressure to crack down on corruption in the army, police and government. (Canadian Press)

Aminullah, who like many Afghans goes by only one name, was accused of passing sensitive military and intelligence information to militants through a man who worked in his office, according to the chief prosecutor assigned to the case. He also faces corruption charges for allegedly selling government property and cooking oil meant for poor people for personal gain, prosecutor Mohammad Nahim Naziry said.

Naziry said Aminullah's brother led a militant cell that attacked Afghan and foreign forces in Bala Murghab.

He said Aminullah was arrested by NATO-backed Afghan troops. NATO said it was looking into the report.

The case is sensitive and delegations from the governor's office, police and intelligence services were expected to travel to Bala Murghab to participate in the investigation.

Deputy provincial governor Abdul Ghani Sabery confirmed the corruption charges but said he had no information that Aminullah was helping militants.