ABU DHABI (AFP) - Three Filipino civil engineers and a South Korean colleague kidnapped in Libya last July have been released and flown to the United Arab Emirates, the UAE Foreign Ministry said on Friday (May 17).

It said the engineers held by unidentified armed groups were freed through joint efforts by Abu Dhabi and military strongman Khalifa Haftar's Libyan National Army.

"The UAE is working on sending them to their home countries," it said, without giving dates for their release or when they were flown to Abu Dhabi.

The ministry said the four Asians had been working on a desalination plant in western Libya, while reports last year said they were seized from a water project in the south of the country.

The Emirates is a supporter of Haftar, whose forces launched an assault in early April to try to take over Tripoli from the internationally recognised Government of National Accord.

Since the 2011 overthrow of Libya's long-time ruler Muammar Gaddafi, foreign workers and diplomats have been frequent targets of attacks or kidnappings by powerful militias or the Islamic State in Iraq and Syria group.