BAMAKO, Jan 14, 2013 (AFP) - Islamists occupying northern Mali on Monday pushed further into the government-controlled south with an attack on the town of Diabaly, 400 kilometres (250 miles) north of the capital, a security source said.

"The Islamists attacked the town of Diabaly today (Monday). They came from the Mauritanian border where they were bombed by the French army," said the Malian security source on condition of anonymity.

He said the Malian army had "urgently" despatched a helicopter to the town.

A regional security source confirmed the attack, which he said was being led by Abou Zeid, a leader of Al-Qaeda in the Islamic Maghreb (AQIM).

"They left the Mauritanian border to avoid raids by French planes," he said.

60 reported killed after French strikes 

The French offensive kicked off on Friday to block the advance of Islamist forces towards the capital from their bases in the north which they have controlled since last April.

On Sunday, French Rafale fighter planes struck bases used by Al-Qaeda-linked fighters in Gao and Kidal, two of the main towns in northern Mali.

Sixty Islamists were killed in Gao alone on Sunday, according to residents and a regional security force.

French warplanes attacked jihadist positions in the town of Nampala some 50 kilometres north of Diabaly, as well as a base in Lere, near the border with Mauritania.