Hundreds of people, including foreign diplomats and activists, paid homage Saturday to a human rights lawyer who was shot dead in Eswatini, sparking alarm over political violence in Africa's last absolute monarchy.

Thulani Maseko, a political activist and fierce critic of authorities in the tiny landlocked nation, was gunned down through the window of his home last Saturday by unknown attackers.

Hours before his murder, King Mswati III had warned activists who defy him not to "shed tears" about "mercenaries killing them".

Diplomatic envoys from the US, European Union, the United Kingdom and the United Nations attended a sombre memorial service on the outskirts of the commercial capital, Manzini.

Lawyers and rights activists from several other African countries, as far afield as Kenya, also travelled to the country - sandwiched between South Africa and Mozambique - to pay their tributes.

A portrait of Maseko was displayed in front of a cream-coloured wooden podium with a spray of white, yellow and red flowers laid out at the bottom.

The UN representative George Wachira said Maseko's killing was a "loss not only to Eswatini but to the world and humanity. We cannot avoid bitterness because Thulani didn't deserve to die in this manner".

"His death shall not be in vain. Thulani was at the core of that theory that through dialogue this country can be fixed," he told mourners.

Maseko, who died aged 52, had spent most of his life fighting state repression and representing opposition activists in court.

In 2014, he was jailed for contempt of court over articles critical of the government and judiciary, but he was acquitted on appeal and released a year later.

At the time of his death, Maseko led a broad coalition of political and civic rights and religious groups created in November 2021 to foster dialogue with the king and seek a way out of the political crisis in the country of 1.2 million people.

- 'Blood on Mswati's hands' -

Eswatini, formerly known as Swaziland, has long cracked down on dissent, with political parties banned since 1973.

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

Maseko's murder drew widespread international outrage and calls for an impartial probe and the prosecution of the culprits.

UK ambassador Simon Boyden, said "human rights defenders, like Thulani, must be able to able to depend on institutions of the state to protect them from violence, from intimidation and from death".

The Vice President of the Law Society in Eswatini, Sdumo Dladla, bemoaned that Maseko "had to die such a violent death while he was preaching against violence".

EU ambassador Dessislava Choumelova called for the "safety of all citizens including political activists".

Paying tribute to the "fallen, giant baobab", Mlungisi Makhanya, president of PUDEMO, a political movement which was banned in 2008, said the killing was "one of the most brutal acts in the history of" Eswatini.

"There is a lot of innocent blood on Mswati's hands. For his atrocities, Mswati and his henchmen must be indicted".

"It is time like this that we must intensify our struggle and exert pressure," said Makhanya speaking via video link from exile.

Maseko was also a senior member of PUDEMO, a political movement pushing for the creation of a constitutional multi-party democracy.

He will be buried early Sunday at 0200 GMT.