Southern Africa's regional bloc SADC called Tuesday for national dialogue and a "comprehensive" probe amid escalating tensions in the tiny kingdom of Eswatini, following the murder of a top rights lawyer and activist.

At the end of talks attended by several region leaders in Namibia's capital, the SADC urged Eswatini's government to "urgently initiate the process of the national dialogue".

They also called for "calm" in the kingdom between South Africa and Mozambique after the killing of human rights advocate Thulani Maseko.

Maseko was shot dead on January 21, sparking alarm over political violence in Africa's last absolute monarchy and drawing condemnation from the international community.

The Southern African Development Community called on Eswatini authorities "to conduct a swift, transparent and comprehensive investigation" into Maseko's killing.

His murder came hours after King Mswati III had warned activists who defied him not to "shed tears" about "mercenaries killing them". There have been no arrests over the killing so far.

Namibian President Hage Geingob, who chairs the SADC's politics, defence and security committee and hosted the talks Tuesday, said the persistent sporadic acts of violence in Eswatini pointed to "an escalation of the tensions".

The talks were attended by Eswatini Prime Minister Cleopas Dlamini, and the presidents of South Africa and Zambia, Cyril Ramaphosa and Hakainde Hichilema.

Maseko, 52, had fought against state repression in Eswatini, a country of 1.2 million people previously known as Swaziland, where political parties have been banned since 1973.

He led a coalition of political and civil rights advocates and religious groups, created in November 2021, to foster dialogue with King Mswati and seek a way out of the crisis.

At least 37 people were killed during weeks of anti-monarchy protests in June 2021.

The Windhoek talks also discussed conflicts in Mozambique and the Democratic Republic of Congo.

In its final statement the SADC "strongly condemned the upsurge of conflicts and activities of armed groups" in the eastern region of DR Congo, where Pope Francis began a visit in Kinshasa on Tuesday.