The APS news agency quotes an unidentified security source for the new death toll and says the fatalities include both Algerian and foreign workers at the remote desert facility.
APS also said Friday that 18 of the hostage takers have been killed.
The militants, meanwhile, offered to trade two captive American workers for two terror figures jailed in the United States, according to a statement received by a Mauritanian news site that often reports news from North African extremists.
The Friday report from the government news agency APS, citing a security official, did not mention any casualties in the battles between Algerian forces and the militants. But earlier it had said that 18 militants had been killed, along with six hostages.
It was not clear whether the remaining foreigners were still captive or had died during the Algerian military offensive to free them that began Thursday.
The desert siege erupted Wednesday when the militants attempted to hijack two buses at the plant, were repulsed, and then seized the sprawling refinery.
Since then, Algeria's government has kept a tight grip on information. It wasn't clear how the government arrived at the latest tally of hostages, which was far higher than the 41 foreigners the militants had claimed as hostages.
The militants had seized hundreds of workers from 10 nations at Algeria's remote Ain Amenas natural gas plant. The overwhelming majority were Algerian and were freed almost immediately.
Algerian forces retaliated Thursday by storming the plant in an attempted rescue operation that left leaders around the world expressing strong concerns about the hostages' safety.
Militants claimed 35 hostages died on Thursday when Algerian military helicopters opened fire as the Islamists transported the hostages around the gas plant.
On Friday, trapped in the main refinery area, the militants offered to trade two American hostages for two prominent terror figures jailed in the United States. Those the militants sought included Omar Abdel Rahman, the blind sheikh who was convicted of plotting to blow up New York City landmarks and considered the spiritual leader of the 1993 World Trade Center bombing, and Aafia Siddiqui, a Pakistani scientist convicted of shooting at two U.S. soldiers in Afghanistan.
But U.S. Defense Secretary Leon Panetta said there would be "no place to hide" for anyone who looks to attack the United States.
"Terrorists should be on notice that they will find no sanctuary, no refuge, not in Algeria, not in North Africa, not anywhere," Panetta said Friday.
Workers kidnapped by the militants came from around the world - Americans, Britons, French, Norwegians, Romanians, Malaysians, Japanese, Algerians.
World leaders have expressed strong concerns in the past few days about how Algeria was handing the situation and its apparent reluctance to communicate.
Terrorized hostages from Ireland and Norway trickled out of the Ain Amenas plant, 800 miles (1,300 kilometers) south of Algiers, the capital. BP, which jointly operates the plant, said it had begun to evacuate employees from Algeria.
"This is a large and complex site and they are still pursuing terrorists and possibly some of the hostages," British Prime Minister David Cameron said Friday in London.
He told British lawmakers the situation remained fluid and dangerous, saying "part of the threat has been eliminated in one part of the site, a threat still remains in another part."
Reader Comments
to our Newsletter