The king was ending his five-nation tour of sub-Saharan Africa on Saturday when the African leaders' initiative was revealed, a Moroccan source said.
Morocco left the Organisation of African Unity (OAU) in 1984 when a majority of African states lined up behind Algeria to recognise the Polisario Front's claim to the territory of Western Sahara, which Morocco claims.
African countries are still divided over whether Morocco, a key regional ally of the US, should be admitted to the African Union, the successor body to the OAU. Algeria continues to support the Polisario Front with materiel and military assistance.
The king's tour took him to five of the countries that have supported Morocco's position, and have established bilateral economic and cultural links with the North African kingdom.
Morocco left the African Union in
1984 over a row with Algeria
The Moroccan source said the leaders King Muhammad met during his visit to Benin, Cameroon, Gabon, Niger and Senegal had called for the return of Morocco "into the heart of the African family", referring to the African Union.
He said they had "praised the king for everything he had done to resolve the crisis of the countries of the Mano river, and for his initiatives in favour of peace in Africa".
In 2002, Morocco organised a summit meeting of the Mano River Union consisting of Guinea, Liberia and Sierra Leone in an attempt to end the conflict that spread across borders in the region.
Morocco also has sent 700 peacekeeping troops to serve under UN mandate in the Ivory Coast and 800 to the Democratic Republic of the Congo.
The source said that during the talks King Mohammed had brought up the question of Morocco's return to the pan-African body, as well as bilateral economic questions and international issues such as Iraq and the Middle East peace process.
Moroccan sources said contacts with the Senegalese president, Abdoulaye Wade, who strongly supports Morocco's claim to the Western Sahara, had been particularly warm.
The king was scheduled to dine with Wade again on Sunday after extending his stay for a private visit.
He concluded the official portion of his visit by receiving the leaders of Senegal's four Islamic confraternities and Catholic Archbishop Theordore-Adrien Sarr of Dakar.