The United States and Morocco on Monday launched the vast annual "African Lion" military exercise, amid heightened tensions between the North African kingdom and neighbouring Algeria.

The exercise, which began in the southern Moroccan region of Agadir and lasts the rest of the month, involves some 7,500 personnel from 10 nations such as Brazil, France and the United Kingdom.

It will include observers from NATO and for the first time, officials from Israel.

Some manoeuvres will take place in Tunisia, Senegal and Ghana, US Africa Command said in a statement.

The "exercise bolsters interoperability among partner nations and supports US military strategic readiness to respond to crises and contingencies in Africa and around the world", it added.

The Moroccan military's second-in-command, General Belkhir El Farouk, said Monday the country needed to tackle "security challenges".

The kingdom will host land, sea and air phases, a paratrooper landing and a weapons of mass destruction response exercise.

Most will take place in Kenitra, near Rabat, but others will be near further south near the Algerian border, according to the Moroccan military.

There will also be a paratrooper landing and an artillery exercise in the desert, near the edge of the disputed Western Sahara and the Sahrawi refugee camps of Tindouf where the Algerian-backed Polisario independence movement is based.

The exercise comes amid heightened tensions over the Western Sahara since US president Donald Trump recognised Moroccan sovereignty over the territory in 2020 in return for Rabat re-establishing ties with Israel.

Algeria responded months later by breaking ties with Morocco, citing "hostile acts" and slamming its neighbour's security cooperation with the "Zionist entity" (Israel).

This month Algiers also scrapped a long-standing treaty with Madrid after the Spanish government broke with decades of neutrality to back a Moroccan plan for autonomy in the desert territory.

Morocco considers it an integral part of the kingdom, while the Polisario has long demanded an independence referendum there.

The former Spanish colony boasts hundreds of kilometres of coastline with rich Atlantic fishing waters, plentiful phosphate resources and a key highway to West African markets.