Two Italians and a Canadian have been kidnapped in Libya's southwestern desert, possibly by a criminal gang, authorities said.

The three, who were working on airport projects, were abducted between the towns of Ghat and Tahala, near the border with Algeria early on Monday, Ghat's mayor Gomani Mohamad Saleh told Reuters.

"The two Italians were working on a runway project at the airport but the Canadian was working on installing air aviation system," he said on Tuesday.

"The security authorities are following the incident closely ... That's all the information we have so far."

Numerous criminal and armed groups are active in Libya's vast southern desert, and al Qaeda-linked Islamist militants have long had a presence across the border between Libya and Algeria.

The Italian foreign ministry said late on Monday that two of its citizens had been abducted in the Libyan desert, without giving further details.

The Canadian government said it was aware of a "troubling yet unconfirmed report of the abduction of a Canadian citizen in Libya".

Local media reports said the three were working for the Libyan branch of Italian firm Contratti lnternazionali Costruzioni SpA. The company declined to comment when contacted.