Authorities in Zambia have suspended the licences of three private broadcasters, including the country's biggest non-public TV station, saying that they had posed a risk to peace and stability during this month's presidential election.

President Edgar Lungu narrowly won the August 11 vote and his opponent Hakainde Hichilema, leader of the United Party for National Development party, have filed court papers to challenge the result, claiming the vote was rigged. The ruling party and the electoral commission have rejected the UPND's accusations.

Zambia's Edgar Lungu wins re-election as rival cries foul

Muvi TV, the largest private television station, Komboni Radio, and Radio Itezhi Tezhi had before, during and after the election conducted themselves in an "unprofessional manner", the Independent Broadcasting Authority said in a statement on Monday.

The broadcasters' actions "posed a risk to national peace and stability", the regulator said without giving further details.

The three private stations closed down were considered opposition mouthpieces.

'Stifling media freedom'

Opposition leader Hichilema criticised the move, saying Zambians were left with only government-owned media sources.

"This closure is meant to stifle media freedom," he said.

"Zambians should unite to protect themselves from a brutal dictator. Let us unite to protect our country from thugs."

The suspended stations have 30 days to appeal the ruling, the regulator said.

READ MORE: Zambia arrests 133 protesters after contested election

The run-up to the presidential poll was tense, with fighting between opposition and government supporters. Police had also broken up opposition campaigning.

According to the Zambian Elections Information Centre, at least three people were killed and many injured during a wave of pre-election violence.

Source: Agencies