U.N. rights chief says Egypt has arrested 1,000

GENEVA (Reuters) - The Egyptian authorities have arrested more than 1,000 people during four days of mass protests against President Hosni Mubarak's three-decade rule, the United Nations' human rights chief said on Friday.

Navi Pillay said Egypt needs to allow its citizens to demonstrate without fear, and to stop trying to silence critics.

She urged the lifting of emergency law, which she said "lies at the root of much of the frustration and anger that has now boiled over into the streets."

"I call on the government to take concrete measures to guarantee the rights to freedom of peaceful assembly and expression, including by restoring free use of mobile phones and social networks," Pillay said in a statement.

Shortly after she made the statement, Egypt announced a 6.00 p.m. to 7.a.m curfew.

Tens of thousands of Egyptians have been protesting in Cairo to demand an end to Mubarak's three-decade rule.

Security forces have fired rubber bullets, teargas and water cannon at protesters who hurled stones back at them and shouted "Down, Down, Hosni Mubarak," witnesses said.

Pillay, a former U.N. war crimes judge, called on Egyptian authorities to investigate alleged use of excessive force which led to at least five civilian deaths.

This week she sent experts to Tunisia to help probe killings and other violations in the run-up to the ousting of President Zine al-Abdine Ben Ali.

"Suppressing citizens' voices, silencing dissent and stifling criticism will not make the problems go away," she said. "Recent events in the region highlight the fact that tackling serious problems by resorting primarily to high-handed security measures only causes them to fester and eventually erupt on a large scale."

(Reporting by Laura MacInnis; Editing by Stephanie Nebehay and Matthew Jones)