The al-Jazeera Arabic news channel has received a tape purportedly from the kidnappers of the BBC's Gaza correspondent Alan Johnston.
Alan Johnston has been missing for more than eight weeks
It contains no new pictures of Mr Johnston, but shows a picture of his BBC ID card.
The tape includes a demand for the release of Muslim prisoners in British jails, and readings from the Koran.
Mr Johnston, 44, was seized in Gaza City on 12 March. He had been on his way home when he was taken at gunpoint.
The tape was delivered to al-Jazeera in Gaza and was made by a group calling itself Jaish al-Islam (Army of Islam).
BBC Deputy Director-General Mark Byford said that the BBC remained deeply concerned for Mr Johnston's safety.
"Fifty-nine days after he was abducted, our sole concern is for Alan's welfare, and for that of his family. What we and they want more than anything else is Alan's safe return," he said.
"We of course welcome any sign that Alan may be alive and well. We profoundly hope that today's news may be a sign that Alan will soon be safely released."
The tape does include one specific demand, the release of Abu Qatada, a Palestinian born Islamic cleric who is suspected of close links to al-Qaeda and is currently held by the UK government as a threat to national security.
JAISH AL-ISLAM FACTS
Small, Islamist armed group operating in Gaza
Splinter group of the Popular Resistance Committees
Seeks liberation of Palestine and an Islamic state
Influenced by, but not affiliated with al-Qaeda
Led by Mumtaz Daghmash, also known as Abu Muhammad, a member of a powerful clan
One of three groups allegedly holding captured Israeli soldier Cpl Gilad Shalit
Until now, the kidnappers have not made their demands public or made any contact with the media.
In April, the previously unheard of Tawhid and Jihad brigades claimed it had executed Mr Johnston, though that claim could not be verified.
The Palestinian government says it has received information that Mr Johnston is alive, and is working for his release.
The BBC's World Affairs correspondent Mike Wooldridge says that not much is known about The Army of Islam, but that it is a known Palestinian group.
He adds that if the tape is authentic, then it does represent a development in the lengthiest kidnapping of a Westerner to take place in Gaza.
News of the tape emerged hours after a senior UK diplomat held talks with Palestinian Prime Minister Ismail Haniya as part of the effort to secure Mr Johnston's release.
Consul-General Richard Makepeace, who is based in Jerusalem, said Mr Johnston's continued captivity remained of "great concern" to the UK.
There have been high-level appeals for his freedom, including from Tony Blair and the United Nations Secretary General Ban Ki-moon.
Mr Johnston joined the BBC World Service in 1991 and has spent eight of the last 16 years as a correspondent, including periods in Uzbekistan and Afghanistan.
He has lived and worked in Gaza for three years and was the only Western reporter permanently based in the often violent and lawless territory.