Attorney General Muhammad Isaaq Aloko met members of a Taliban peace negotiation team in Dubai despite being told by the Presidential Palace not to attend the meeting, the official said.
“He was instructed not to go,” said the official, who declined to be identified.
A prominent member of parliament also said Aloko had been sacked.
But an official in Aloko’s office denied that his boss had been dismissed, saying he was at the Presidential Palace “celebrating Independence Day” on Monday.
Peace talks between the Karzai administration and the Taliban are seen as crucial to averting another round of war as Afghanistan’s NATO-led force prepares to end its military mission by the end of next year.
Talks with the Taliban began in 2010 but they have been marked by a series of missteps, delays and allegations of plotting and interference.
The senior Afghan official said some senior cabinet members were trying to persuade Karzai to reverse his decision to dismiss Aloko.
The meeting in Dubai was in the first week of August and involved other prominent Afghans including members of the government’s High Peace Council, which Karzai set up in 2010 to pursue talks with the Taliban.
Aloko had been Karzai’s attorney general since 2008.
Karzai will travel to Pakistan on August 26–28 in an attempt to patch up ties and breath life into the stalled Afghan peace process.