A South African man convicted of terrorism and treason in Swaziland must be allowed to return to his home country, the ANC Youth League said on Thursday.

"We in the Congress Youth League know that Comrade [Amos] Mbedzi is only guilty for supporting the struggle of the Swazi people against the repressive tinkhundla regime," spokeswoman Khusela Sangoni-Khawe said in a statement.

The tinkhundla system of local governance in Swaziland is based on traditional authorities.

Nelson Kgwete, spokesman for the department of international affairs, confirmed that Mbedzi was convicted by a Swazi court last week.

"We are aware of the conviction and our embassy in Swaziland has been in contact with him, during the trial and after the conviction."

Last Wednesday news agency AFP reported that Mbedzi was found guilty of planning a bomb attack against King Mswati III in 2008.

The bomb exploded while Mbedzi was allegedly on his way to plant the incendiary device, seriously injuring him.

Sangoni-Khawe said the charges against Mbedzi were baseless and that he had only participated in demonstrations aimed at ending the dictatorship of Swaziland's absolute monarchy.

She said the ANCYL called for the government of Swaziland to release all political prisoners and allow exiles to return.

"The ANCYL calls upon its members to intensify their support and solidarity with the oppressed peoples of Swaziland by taking part in an action to demand a democratic Swaziland, which will soon be organised at the border of South Africa and Swaziland."