The US military has moved a team of marines from Spain to southern Italy as a precautionary step in case the US embassy in Libya comes under threat, officials said Wednesday.

The contingent of nearly 200 marines is part of a newly-created "crisis response" force set up in the wake of a deadly attack on a US diplomatic outpost in the Libyan city of Benghazi in 2012.

The State Department has requested the move amid growing concerns over violence in Libya, but there was no imminent plan to evacuate the embassy in Tripoli, an administration official said.

"We're seeing a deterioration of the security situation there," the official, who spoke on condition of anonymity, told AFP.

The team, equipped with four tilt-rotor Osprey aircraft as well as two KC-130 refueling tankers, arrived at the US naval air station in Sigonella in Italy on Tuesday, Pentagon spokesman Colonel Steven Warren told reporters.

The deployment was ordered as a "prudent measure" due to "the general unrest in Northern Africa," Warren said.

He declined to say if the move was focused on a particular country.

The US troops were drawn from a force in Moron, Spain, the Marine Air-Ground Task Force Crisis Response unit. The force helped evacuate staff from the US embassy in South Sudan last year.

Libya's central government has struggled to assert its authority over the vast, mostly desert country, which is effectively ruled by a patchwork of local militias and awash with weapons.

In March, the authorities acknowledged for the first time the existence of "terrorist groups" in Libya, particularly in Benghazi and in Derna, an eastern city with a history of Islamist militancy.

Saudi king reshuffles defence posts
Riyadh (AFP) May 14, 2014 - Saudi Arabia's King Abdullah on Wednesday reshuffled top defence posts, removing the deputy minister and the chief of staff, state news agency SPA reported.

He also appointed his son Prince Turki as governor of Riyadh region, SPA said.

Prince Salman bin Sultan bin Abdul Aziz was removed from his post as deputy defence minister "upon his request," SPA said, citing a royal decree.

He was replaced by Prince Khaled bin Bandar bin Abdul Aziz, the governor of Riyadh.

The outgoing deputy minister is a son of the late Crown Prince Sultan, who served as a defence minister for nearly five decades.

SPA said the king also removed the chief of staff, General Hussein al-Qabeel, who was retiring, and replaced him with his deputy. General Fayad al-Rawyli.

The defence overhaul came a month after the king removed the oil-rich Gulf state's powerful intelligence chief, Prince Bandar bin Sultan.