Reports from the besieged rebel-held Libyan city of Misrata say government forces have used anti-vehicle land mines in a renewed attack.
The use of Chinese anti-vehicle mines was verified by Human Rights Watch, the BBC reports.
They were dropped by mini-parachutes from rockets that open during flight, according to the New York Times.
Rebels said forces loyal to Libyan leader Muammar Gaddafi had also bombed fuel tanks in Misrata, setting them on fire.
NATO forces had recently cleared anti-shipping mines which had been scattered off the coast of the port.
Misrata is Libya's third-largest city and a key port. It is largely controlled by rebels fighting to topple Colonel Gaddafi, but has been under siege for weeks.