LUANDA, Angola (CNN) -- A U.N.-chartered cargo plane that crashed just after takeoff in Angola has been located mostly intact, and there is a chance for survivors, a U.N. spokesman said Tuesday.

But a rescue team can't enter the rebel-held territory where the plane went down, unless government and rebel forces agree to a cease-fire.

The United Nations has asked for a 48-hour cease-fire, said Issa Diallo, head of the U.N. Observer Mission in Angola.

"If they cannot allow 48 hours, 24 will suffice," Diallo said. "We are still hopeful, but time is of the essence. We should not let these people die that way."

The C-130 transport plane crashed Saturday, just 10 minutes after taking off from the central highland city of Huambo, about 500 kilometers (310 miles) southeast of the capital, Luanda. The plane was headed for Saurimo in Angola's northeast with 10 passengers and four crew members aboard.

The cause of the crash is not known.

The region has been the scene of fierce fighting between the Angolan government and rebels from the National Union for the Total Independence of Angola (UNITA).

"The government is saying there is not much we can do, because the plane has crashed in UNITA-held areas," Diallo said, adding that the rebels had confirmed receipt of the cease-fire request.

"We've spoken to everyone we can on both sides, but we're still waiting for a green light," said U.N. spokesman Hamadoun Toure.

The passengers on board included three Angolans, two Russians, an Australian, an Egyptian, a Cameroonian, a Zambian and a Namibian. The crew was made up of a South African, an Angolan, a Bolivian and a Filipino.

Eight passengers were members of the U.N. mission. Two others were employed by a private communications company, Dinacom, which works with the United Nations.

U.N. officials said Monday they had received morse code SOS signals from the aircraft, but communications specialists could not determine if the signals were automatic transmissions or were being sent manually.

Angola has been ravaged by conflict since 1975, when it gained independence from Portugal. The U.N. mission was set up in the country to monitor a 1994 peace deal. The latest round of fighting broke out December 4.

Reuters contributed to this report.