Nato powers rejected Moammar Gaddafi’s call for a cease-fire and negotiations yesterday, saying they need “actions not words,” and aid ships were prevented from docking in a besieged coastal city while the alliance swept the port for mines.

Human Rights Watch said two mines had been destroyed by Nato forces combing the Misrata port while a third was being closely monitored. The alliance did not give details but said the process would take time.

“Mine clearance is a precise and highly skilled task, so it will take time to do this in a safe and effective way,” Nato spokeswoman Carmen Romero said.

Nato also bombed a government complex that included the state television building in Tripoli. The Libyans alleged the strike was meant to kill Gaddafi as his address was broadcast live on state TV, but the TV building was not damaged and Gaddafi spoke from an undisclosed location.

In a rambling pre-dawn speech that lasted for more than an hour, Gaddafi appeared both subdued and defiant, repeatedly pausing as he flipped through handwritten notes.

“The door to peace is open,” Gaddafi said, sitting behind a desk. “You are the aggressors. We will negotiate with you. Come, France, Italy, UK, America, come, we will negotiate with you. Why are you attacking us?”

He said Libyans have the right to choose their own political system, but not under the threat of NATO bombings.

Rebel leaders have said they will only lay down their arms and begin talks on Libya’s future after Gaddafi and his sons, some of whom hold powerful positions in the country, step aside. Gaddafi has repeatedly refused to resign.

A rebel spokesman, Jalal al-Galal, called the cease-fire offer a publicity stunt.

“We don’t believe that there is a solution that includes him or any member of his family. So it is well past any discussions. The only solution is for him to depart,” he said.

Gaddafi denied his forces had killed Libyan civilians. But even as he called for a cease-fire, he appeared to dismiss the possibility of one, saying his enemies were al-Qaida operatives who did not understand what a truce meant.

He promised the young rebels fighting his regime that if they gave up their guns, he would give them cars and money, saying they were children “tricked” by NATO promises.

In Brussels, a NATO official said the alliance needed “to see not words but actions,” and vowed NATO would keep up the pressure until the UN Security Council mandate on Libya is fulfilled. The alliance has promised to continue operations until all attacks and threats against civilians have ceased, all of Gaddafi’s forces have returned to bases and full humanitarian access is granted.

The NATO official, who spoke on condition of anonymity according to policy, noted that Gaddafi’s forces had shelled Misrata and tried to mine the city’s port just hours before his speech. The city of 300,000 is the main rebel stronghold in western Libya and has been under siege for two months.

With the rebels holding much of eastern Libya, Gaddafi needs to consolidate his hold over the western half, including Misrata and a mountainous region on the border with Tunisia.

“The regime has announced cease-fires several times before and continued attacking cities and civilians,” said the official who could not be named under standing regulations. “All this has to stop, and it has to stop now,” the official said, adding that a cease-fire had to be “credible and verifiable.”

The British Foreign and Commonwealth Office said Gaddafi needs to stop besieging cities and attacking the Libyan people before any political transition can be achieved.

Italian Foreign Minister Franco Frattini didn’t mention the truce offer in an interview yesterday on Italian state TV but reaffirmed the need for NATO’s intervention because of the “horror” perpetrated by Gaddafi’s regime.

The Italian Foreign Ministry is hosting a one-day summit on Libya next Thursday, bringing together the main international players in the six-week NATO military campaign, including US Secretary of State Hillary Rodham Clinton.

On Friday, NATO intercepted boats laying anti-ship mines in the waters near Misrata. A NATO warship could be seen in the distance while a smaller boat circled the harbour’s entrance yesterday.

Rebel security officials said NATO ships had been combing the waters since about 1 a.m. One of the mines was destroyed nearly two miles away from the port, causing a huge explosion that sent water and a huge plume of gray smoke into the sky, the officials said.

The port is Misrata’s only lifeline, and hundreds of desperate migrants and residents waited for news that it could reopen.

“All the humanitarian missions are stopped now because they cannot get any humanitarian aid inside,” said Fadl Moukadem of the international aid group Mercy Corps.

Peter Bouckaert of Human Rights Watch said the International Organization of Migration and UNICEF had boats waiting to go to Misrata but NATO wanted to destroy a third mine before reopening the harbor.

Moussa Ibrahim, the Libyan government spokesman, said he was unaware of the attempted mine-laying. However, he said the government is trying to prevent weapons shipments from reaching the rebels by sea. Asked whether aid vessels would also be blocked, he said any aid shipments must be coordinated with the authorities and should preferably come overland.

Gaddafi’s forces have repeatedly shelled the port area and his ground troops are deployed on the outskirts of Misrata, after having been driven out of the downtown area by the rebels last week.

Heavy fighting continued in the southern part of the city near the airport and frequent large booms could be heard in downtown from that part of town.

Hassan al-Bari, 21, who lay in the hospital screaming from pain from a three inch gash on his cheeks, said Gaddafi’s forces were just outside the airport. He was wounded in a mortar strike there.

The hospital contained two dead and four injured from fighting.