Anthony Shadid, New York Times' Beirut bureau chief, and three colleagues are missing in Libya [New York Times]

Four journalists reporting on the conflict in Libya for the New York Times are missing, the newspaper says.

The four include Stephen Farrell, a reporter and videographer who was kidnapped by the Taliban in Afghanistan in 2009 and rescued by British commandos.

Anthony Shadid, the paper's Beirut bureau chief and a two-time Pullitzer Prize winner, and two photographers, Tyler Hicks and Lynsey Addario, are also missing.

The four haven't been in touch with editors since Tuesday morning. The paper said it had received second-hand reports that members of its reporting team had been swept up by Libyan government forces in Ajdabiyah, the scene of fierce fighting in recent days.

But the Bill Keller, the paper's executive editor, said the Times had not been able to confirm that information.

“We have talked with officials of the Libyan government in Tripoli, and they tell us they are attempting to ascertain the whereabouts of our journalists,” said Keller.

“We are grateful to the Libyan government for their assurance that if our journalists were captured they would be released promptly and unharmed.”

Meanwhile, an Iraqi journalist working for the UK's Guardian has been released by Libyan authorities, the newspaper said on Wednesday.

Ghaith Abdul-Ahad was detained by Libyan authorities earlier this month while reporting on fighting in the west of the country. A Brazilian journalist, Andrei Netto, detained with Abdul-Ahad was released last week.

The editor of the Guardian, Alan Rusbridger, said: "We're delighted that Ghaith has been released and is safely out of Libya. We are grateful to all those who worked behind the scenes to help free him after his ordeal."

Casualties of the conflict in Libya include an Al Jazeera cameraman, Ali Hassan Al Jaber, who was shot and killed in an apparent ambush near the rebel-hend city of Benghazi.

Last week three BBC journalists were beaten and subjected to mock executions after being detained by Libyan soldiers and secret police at a checkpoint, the BBC said.