(CNN) -- The number of people killed in Egypt's protests against President Hosni Mubarak could be two or even three times higher than previously estimated, a human rights activist on the ground warned Thursday.

Human Rights Watch has confirmed about 300 deaths, said Hossam Bahgat of the Egyptian Initiative for Personal Rights. But independent researchers have not been able to get information from many places, he said.

"We can definitely say that the most conservative number is 300. It could be twice or three times, if not more," he said.

Human rights activists have been visiting hospitals and morgues to try to get an accurate count, especially after a particularly brutal round of violence January 28-29, he said.

But there are many places where they have not been able to reach or where they found officials unwilling to give them information, he said.

Tom Porteous of Human Rights Watch advised against focusing exclusively on the number killed.

"A death toll by itself does not give an indication of the abuses that took place," he said in the same briefing. "The number of people who died from close-range shooting is an indication that there is a need for investigation."