Mr. Abdullah arrived in Egypt amid rumors of fresh negotiations between the rebels and representatives of the Qaddafi government in Tunisia and a visit to Tunis, the capital, by the United Nations envoy to Libya. The envoy, Abdelilah al-Khatib, said that he discussed the conflict with Tunisia’s prime minister and that he would meet with some Libyans in Tunisia, although he did not offer specifics.

“I confine my official talks to the two parties to the crisis,” he said.

Successive rounds of negotiations, most of them conducted in secret, have borne little fruit. But they are growing in urgency, with concerns mounting that the Libyan conflict will become bloodier as the front lines approach Tripoli, the capital. Two senior diplomats with knowledge of the talks, who spoke on the condition of anonymity, said Colonel Qaddafi had given no sign that he was serious about negotiating an end to the conflict. At the same time, the rebels, emboldened by their gains in recent days, are losing incentive to make concessions.