Libyan rebels have captured the airport in Misrata from Qaddafi troops Wednesday, the BBC reports.

Witnesses tell the BBC that hundreds of rebels in the besieged city were celebrating after driving Libyan troops out.

This comes as U.N. chief Ban Ki-moon called for "an immediate, verifiable cease-fire" in Libya on Wednesday and said Muammar al-Qaddafi's government had agreed to another visit by a special envoy.

The secretary-general said he spoke with Libya's prime minister by phone late Tuesday to urge a cease fire and demand unimpeded access for U.N. humanitarian workers there. He also called on Qaddafi's forces to stop attacking civilians.

Ban said the prime minister, Baghdadi al-Mahmoudi, agreed to receive a special U.N. envoy who would now travel to Tripoli to undertake "negotiations for a peaceful resolution of the conflict and unimpeded access for humanitarian workers."

The U.N. chief said it would be the seventh such visit to Libya by his envoy, Abdul Ilah Khatib, a Jordanian politician and economist who has twice served as foreign minister.

Ban pronounced the uprisings across North Africa and the Arab world a rare but fragile opportunity to advance democracy and human rights. He said the movements must be "nurtured and carefully handled by the people who created it."

Ban called on all nations' patrol ships off the Libyan coast in the Mediterranean Sea to help prevent more tragedies like the apparent deaths of all 600 African migrants aboard an overcrowded ship to Europe that broke apart within sight of the Libyan capital.

"I'm disturbed by accounts of people fleeing the fighting, losing their lives at sea," Ban said. "I ask patrol vessels in the Mediterranean not to wait for distress signals to offer help. Any boat leaving Libya should be considered a boat in need of assistance and protection."

Ban said he approved of President Barack Obama's decision to send Navy SEAL commandos into Pakistan to kill Al Qaeda leader Usama bin Laden.

"This operation was conducted under extremely difficult, extremely dangerous situations, and that's why I expressed my relief that justice was done to this mastermind of crimes," Ban said.

Asked whether he believes NATO coalition forces are exceeding their U.N. authorization or should step their attacks to oust Qaddafi, Ban said those forces have a mandate "to take necessary military action to prevent Qaddafi forces (in their attempt) to kill those civilian population(s)."

In Brussels, NATO welcomed Ban's call for a cease-fire.

"Of course we agree with the U.N. Secretary-General," NATO spokeswoman Carmen Romero said. "NATO would like to see an immediate end to the violence since our mandate is to protect civilians."

"There can be no solely military solution to the crisis in Libya," she said.

NATO Secretary-General Anders Fogh Rasmussen, who is on a visit to the United States, said last month that any cease-fire must be verifiable and credible, and that there must be a complete end to attacks against civilians.

The Associated Press contributed to this report.