* NATO shifts air strike targets in urban areas
* Alliance says 600 government targets damaged in a month
By Justyna Pawlak
BRUSSELS, April 29 (Reuters) - NATO accused Libyan leader Muammar Gaddafi’s forces on Friday of laying mines in Misrata harbour in an attempt to block humanitarian access to the besieged city.
A senior NATO official said alliance vessels in the Mediterranean Sea had intercepted small boats in the waters off Misrata, the biggest rebel stronghold in western Libya.
“Only this morning ... an incident took place in which it became apparent some vessels, which we assume were pro-Gaddafi forces, were laying mines near the harbour,” NATO’s director of operations in Libya, Brigadier Rob Weighill, told reporters.
“This is another clear demonstration of the Gaddafi regime completely ignoring international law and also an effort to prevent humanitarian assistance going into Misrata to help the beleaguered population,” the British officer said.
Gaddafi’s forces, fighting a rebellion since mid-February, have repeatedly tried to retake Misrata but Weighill said rebels had made progress in recent days. They have been helped by NATO air strikes on Gaddafi’s troops.
“The rebels have expanded their perimeter significantly over the past week. To suggest they are winning would be overly optimistic,” he said. “They are putting up a very spirited fight.”
Weighill said Gaddafi’s forces had damaged important utilities in Misrata, such as a desalination plant, cutting off access to fresh water, and the city’s sewage system.
Government forces, NATO said, had used inflatable boats to place the mines, leading Misrata port authorities to close down the port, forcing the diversion of two humanitarian aid ships.
Aid agencies have brought thousands of people from Misrata since fighting began there, and hundreds of Libyans are still waiting to be evacuated, according to U.N. estimates.
Separately, a NATO spokeswoman said the alliance was concerned about Gaddafi forces crossing into neighbouring Tunisia. [ID:nLDE73S12B].
“We would condemn any violation of territorial integrity of a sovereign nation and we call for restraint,” Carmen Romero said.
Pro-Gaddafi forces fired shells into Dehiba and a group of them drove into the Tunisian town, chasing rebels from the restive Western Mountains region of Libya.
A NATO official said the alliance was planning an operational shift in the coming days, concentrating on large urban areas which have not recently been top targets.
The official declined to specify which Libyan cities would be involved, but Weighill said results would be seen in “the next few days”.
Since taking over operations on March 31, NATO has conducted more than 4,000 sorties over Libya under a United Nations mandate which gave it the authority to do everything necessary to protect Libyan civilians from attack by Gaddafi’s forces.
Weighill said NATO had struck some 600 targets, including 220 government tanks, 70 surface-to-air systems and 200 ammunition facilities. (Reporting by Justyna Pawlak; editing by Tim Pearce)