WASHINGTON (Reuters) - The planned exchange of two senior Taliban commanders and a leader of the Haqqani militant group for an American and an Australian kidnapped in Afghanistan in 2016 has not taken place, a diplomat and a former Afghan official said on Wednesday.

The diplomat, who spoke to reporters on condition of anonymity, declined to provide any details about why the planned exchange, which Afghan President Ashraf Ghani announced on Tuesday, did not occur.

The U.S. State Department did not immediately respond to a request for comment, nor did the Afghan embassy in Washington.

“We hope the Taliban immediately releases the hostages,” a spokesman for the Australian Department of Foreign Affairs and Trade said.

He said Australia appreciated Ghani’s concern for the hostages - Australian citizen Timothy Weeks and U.S. citizen Kevin King, professors kidnapped by the Taliban in August 2016 from the American University of Afghanistan in Kabul.

The Afghan government’s decision to free Anas Haqqani and two other Taliban commanders, Haji Mali Khan and Hafiz Rashid, was taken in the hope of securing direct talks with the Taliban, which has refused to engage with what it calls an illegitimate “puppet” regime in Kabul. All three were captured in 2014.

In return, King and Weeks were to be freed.