Spain said Friday it was starting negotiations with Washington to host a permanent US Marines intervention force for deployment on missions to Africa.

The Spanish government said it was ready to permanently extend an agreement under which the force has been based at Moron de la Frontera, near Seville in southern Spain.

The government approved negotiations to amend the two countries' 1988 defence accord, Deputy Prime Minister Soraya Saenz de Santamaria said after a cabinet meeting.

Spain's foreign and defence ministers will negotiate the amendment, as requested by the United States last month, "with a view to hosting the deployment for an indefinite time", she told a news conference.

The US force was first stationed at Moron in April 2013 in the wake of a deadly attack on the US consulate in Benghazi, Libya the previous year. Its temporary status was renewed last year.

Its duties in Africa include protecting embassies, rescuing military personnel and evacuating civilians or intervening in conflicts and humanitarian crises.

The force is made up of 800 Marines plus air support, including MV-22 Osprey vertical take-off transport planes.

The contingent aims to strengthen vigilance in "an area that is a top security priority for our partners and neighbours but also for Spain", Saenz said.

Spanish newspaper El Pais reported that the new agreement could increase the strength of the contingent to 3,000 personnel if needed.

The force operates under the orders of the US military's Africa command, based in Germany.