* Rebels say rain of rockets hit city, killing 23
* Clinton says NATO must stay united
* Rescue ship heads to Misrata
* NATO bombs Tripoli, Gaddafi tours city (Adds Gaddafi appearance, Hague, Koussa, NATO bombing)
By Mussab al-Khairalla and Alexander Dziadosz
TRIPOLI/BENGHAZI, Libya, April 14 (Reuters) - Libyan rebels begged for more NATO air strikes on Thursday and said they faced a massacre from government forces, who blasted the besieged city of Misrata with a barrage of missiles.
NATO foreign ministers met and pledged their support for more air strikes, but failed to paper over cracks in their alliance over how to proceed in a three-week old campaign that has failed to dislodge Libyan leader Muammar Gaddafi.
NATO planes bombed the capital Tripoli, where Libyan state television showed footage of a defiant Gaddafi cruising through the streets in a green safari jacket and sunglasses, pumping his fists and waving from an open-top vehicle.
Rebels said a hail of rockets fired by besieging forces into a residential district of Misrata, Libya’s third largest city, had killed 23 civilians, mostly women and children.
“Over 200 Grad missiles fell on the port area, including residential neighbourhoods near the port. They shelled this area because the port is Misrata’s only window to the outside world,” a rebel spokesman using the name Ghassan said by telephone.
“The destruction there was huge. I was there and saw for myself,” he said, adding that the port had been shut.
Aid organisations warn of a humanitarian disaster in Misrata, the lone major rebel bastion in western Libya, where hundreds of civilians are said to have died in a six-week siege.
In Tripoli, Reuters journalists heard four blasts and anti-aircraft fire and saw plumes of smoke to the southeast when NATO aircraft struck.
A NATO official said pilots had hit an anti-aircraft battery 40 km (25 miles) south of the city and two other targets “closer to the city centre”. Libyan television said there were civilian casualties. This could not be confirmed.
The Western alliance has struggled to maintain unity, especially since Washington took a back seat in the air campaign on March 31, reducing its role in strikes and handing command to NATO. Britain and France complain that allies are not contributing enough firepower.
NATO foreign ministers met in Berlin, where U.S. Secretary of State Hillary Clinton expressed concern about “atrocities” in Misrata and called for “resolve and unity” against Gaddafi, but gave no hint Washington would resume a bigger military role. The NATO foreign ministers promised in a joint declaration to provide “all necessary resources and maximum operational flexibility” for the air campaign to maintain a “high operational tempo against legitimate targets”.
But several allies rebuffed calls from France and Britain to contribute more to the air attacks, conducted under a United Nations mandate to protect civilians. U.S. officials denied allied commanders had requested greater resources.
France cited Spain, Italy, the Netherlands and Sweden among allies who could do more. NATO commanders say they need about 10 more strike aircraft.
More on Middle East unrest: [nTOPMEAST] [nLDE71O2CH]
Libya Graphics link.reuters.com/neg68r
Interactive graphic link.reuters.com/puk87r
“A massacre ... will take place here if NATO does not intervene strongly,” a rebel spokesman in Misrata told Reuters by phone. Reports of casualties are hard to verify in the isolated city.
Al Jazeera television showed hundreds of Misrata residents demonstrating after the dawn attack. “The blood of martyrs will not be in vain,” they chanted, waving the rebel flag.
The International Organisation for Migration said a small rescue ship had reached Misrata to begin evacuating nearly 8,300 stranded migrants there, many in “an extremely poor state”.
“We are not sure whether we can offload the aid or not, given the shelling,” said spokeswoman Jemini Pandya said.
Migrants from Egypt, Niger, Bangladesh, Ghana, Sudan and Nigeria have been stranded in Misrata, living in the open for weeks with limited food and no clean water. The IOM ship can carry only 800 people at a time and funds cover only two trips.
Libyan state television said NATO aircraft also hit the al-Assah area, 170 km west of Tripoli. It gave no details.
British Foreign Secretary William Hague said after the Berlin meeting he was hopeful more countries would contribute to the strike force. “It’s not unreasonable to ask other nations...to make additional contributions,” he said.
Spain said it had no plan to join the seven NATO states that have conducted ground strikes. Italy, Libya’s former colonial power, expressed reluctance to launch attacks.
French Defence Minister Gerard Longuet has said Gaddafi’s attacks cannot be stopped without U.S. participation in strikes on his tanks and artillery.
Amid a flurry of diplomacy over Libya, U.N. Secretary General Ban Ki-moon, EU foreign policy chief Catherine Ashton, Arab League head Amr Moussa and officials from the African Union and Organisation of the Islamic Conference pressed for a ceasefire and a political solution after meeting in Cairo.
NATO members are also divided over whether to arm the rebels. Spanish Foreign Minister Trinidad Jimenez said this was not allowed under the U.N. resolution authorising strikes.
France says the resolution permits arming the rebels, although it has no plans yet to do so. A U.S. official said there was no consensus on whether to arm the rebels, but reiterated President Barack Obama’s statement that he “hasn’t ruled it out and hasn’t ruled it in”.
Britain said former Libyan Foreign Minister Moussa Koussa, who fled to the West, would no longer be subject to European Union sanctions, in a move to encourage other defectors. (Additional reporting by Dina Zayed in Cairo, Hamid Ould Ahmed in Algiers, Richard Lough in Rabat, James Mackenzie in Rome, Brian Rohan in Paris and David Brunnstrom, Matt Spetalnick and Adrian Croft in Berlin; Writing by Barry Moody and Peter Graff; editing by David Stamp)