The families of two South African engineers imprisoned in Equatorial Guinea have launched a campaign for their urgent release.
Frik Potgieter (54) and Peter Huxham (55) were arrested in February last year on what their families say are trumped-up drug charges.
It was alleged during the court case that drugs had been found in their luggage.
Their arrest came days after luxury assets belonging to Equatorial Guinea’s Vice-President Teodore Nguema Obiang were seized in South Africa.
They asked the Equatorial Guinea authorities for comment.
Mr Obiang’s yacht and two villas in Cape Town were impounded in execution of a court ruling.
The yacht has reportedly since been released but the villas remain impounded.
The South African expatriates were working for an oil and gas company when they “were illegally arrested and imprisoned” on “fake drug charges”, their petition says.
“Frik and Peter are innocent of these charges, and have been caught in a diplomatic battle between South Africa and Equatorial Guinea,” they say in their campaign on the petition platform change.org.
They have called for the assistance of the South African government as well as the UK government, as Mr Huxham has dual nationality.
South Africa’s Foreign Minister Naledi Pandor last month asked for the release of the two men during her visit to the Equatorial Guinea last month.
A ministry statement in early May said the minister had raised “concerns regarding the incarceration of two South African citizens in the country”.
It noted that the two countries were continuing to engage on the matter.
But the family says while that had raised their hopes, since then “there has been no movement”.
The ministry did not immediately respond queries regarding the matter.
The South Africans were imprisoned for 12 years and fined $5m (£4m) each last June.
Their families say they are being held in a prison reserved for political prisoners in Mongomo in the east of the country.
“[There is] no doubt that their arrests are aimed at forcing South Africa to release the vice-president’s properties,” South African media quoted a family spokesman, Shaun Murphy, as saying.
The families say their lawyers had lodged an appeal against the court proceedings and the sentences, which they termed “excessive”.