His visit came as talks between Libyan rivals were set to restart Friday evening in Bouznika, near Rabat, according to a Moroccan official.

Washington sees the kingdom as a key ally in a region destabilised by years of conflict in Libya and turmoil in the Sahel region.

Esper on Friday signed a 10-year military cooperation deal with Rabat, two days after signing a similar deal in Tunisia.

"Now more than ever, our two nations are working closely together to tackle the challenges of the increasingly complex security environment, ranging from counterterrorism and other transnational threats to regional instability and broader strategic challenges," he said before the signing.

Moroccan Foreign Minister Nasser Bourita hailed the deal as "reaffirm(ing) clearly that our alliance is strong and here to stay", citing major challenges including "terrorism, violent extremism and all kinds of separatism".

During his visit, Esper also met army chief Abdelfattah Louarak and the minister in charge of defence administration, Abdellatif Loudiyi.

The goal of his visit was to reinforce cooperation between the United States and Morocco, which already hosts the largest annual US joint military exercise in Africa, "African Lion" -- although this was cancelled this year due to the novel coronavirus pandemic.

The US is Morocco's top arms supplier, selling it combat aircraft, ships, tanks and armoured vehicles.

- Libya talks -

Esper also signed a 10-year military cooperation deal with Tunis on Wednesday, hailing their collaboration over the conflict in Libya.

In a speech at an American war cemetary in Carthage, he accused US rivals China and Russia of using "malign, coercive, and predatory behaviour" to undermine African institutions and expand their "authoritarian influence".

But on Thursday, he visited Russian and Chinese ally Algeria, becoming the first US defence chief to do so since Donald Rumsfeld almost 15 years ago.

Algeria is trying to reactivate its role on the regional diplomatic scene, including as a mediator in the conflicts in Mali and Libya.

Its arch-rival Morocco hosted talks last month between parliamentary representatives of the major adversaries in Libya's complex conflict, the Tripoli-based Government of National Accord (GNA), led by Fayez Mustafa al-Sarraj, and the eastern Libyan commander Khalifa Haftar

The meetings came five years after Morocco hosted peace talks that led to the creation of the UN-recognised GNA in a bid to end what has now been almost a decade of violence since the 2011 toppling of dictator Moamer Kadhafi.

Morocco's foreign minister also visited Mali last month, meeting transitional president Bah Ndaw and his deputy, Colonel Assimi Goita, leader of a military coup that overthrew President Ibrahim Boubacar Keita in August.