Updated

Swaziland police arrested an opposition leader and deported foreign trade unionists in a crackdown denied by authorities, South Africa's main union said Friday, just two weeks before elections in the absolute monarchy.

South African workers' federation Cosatu said Mario Masuku, the leader of Swaziland opposition party Pudemo, was detained Thursday en route to a protest against King Mswati III's government.

"The Pudemo president was arrested on his way to the border blockade near Oshoek," in northeast Swaziland, the union's international secretary Bongani Masuku told AFP.

But Swazi police spokeswoman Wendy Hleta said the claim was "lies."

The International Trade Union Confederation, of which Cosatu is a member, had planned an investigation into Swazi workers' rights and democracy for Friday.

But Cosatu said security forces broke up the meeting and deported trade unionists including its representative Jay Naidoo, who was a South African cabinet minister under Nelson Mandela.

"They have been kicked out of the country," said Masuku.

Authorities could not be reached for comment on the incident, which took place in a hotel in Swaziland's second city, Manzini, but government spokesman Percy Simelane confirmed Naidoo had been briefly detained for questioning Thursday night.

Simelane denied however that Naidoo had been deported, saying he was in his hotel room waiting to catch a flight.

Africa's last absolute monarchy, which Friday celebrates independence 45 years ago from Britain, votes in parliamentary elections on September 20.

But critics say the polls are a sham, since Mswati controls parliament and political parties have been banned for decades.

Mswati last week described his kingdom as a "monarchial democracy."

Labour groups and the Swazi diaspora have been campaigning for democratic reforms in the tiny mountain kingdom, which is surrounded by South Africa and Mozambique.

In a report released Friday, Britain-based think tank Chatham House urged political and economic change in the kingdom, which it labelled "Southern Africa's Forgotten Crisis."

A bloated civil service and an expensive royal household have crippled the impoverished kingdom's economy.

"The single greatest risk for the next government is to believe that the country can continue to be ruled effectively without introducing reforms," the report said.

Mswati's personal fortune reportedly amounts to $200 million (152 euros), while 70 percent of his subjects live below the poverty line, according to the UN.

A Swazi newspaper editor and former advisor to Mswati who fled the kingdom in February 2012 said everything revolved around the king in the "monster that is Swaziland."

"Fear is what the king uses to rule Swaziland. There is no freedom of expression in Swaziland," said Musa Ndlangamandla, who was sacked as editor of the state-controlled Swazi Observer after he published interviews with leaders of banned pro-democracy groups.

But Chatham's Africa research director Alex Vines said many reform-minded activists and politicians would take part in the upcoming polls, which could bring about change.

"After 20 September there will be more MPs in Swaziland that have a reformist vision," he said at the release of the report in Johannesburg.

"The king might have to consider taking some of those into government."