CAPE TOWN, South Africa — Robben Island was chosen as a prison for Nelson Mandela because of its isolation.

These days it’s a tourist attraction — but reaching it over the past week has become almost as difficult as escape once was, due to mechanical problems and bad weather.“Next ferry, Jan. 13,” read a small sign at the ticket counter yesterday morning, prompting groans of disbelief from tourists who had hoped to see what has become a symbol of courage and hope.

“Robben Island is like our Statue of Liberty,” said Ismail Abdullah, who works for a tour company. “It’s heartbreaking to tell people they can’t go there. We want to show the world that we are now a liberated place, and we can’t.”

After an avalanche of criticism from the tourist industry and crisis talks with government officials, the Robben Island Museum, which is responsible for the island, said late yesterday it would run the ferries for two hours each day longer than scheduled to catch up with the backlog.

Chief Executive Officer Paul Langa said that by Saturday the ferry service should be back on track. He said that by Monday an additional boat would be brought into service.

“We will be able to accommodate everyone,” he told The Associated Press.

Dozens of boat trips have been scrapped in the past week and hundreds of tickets — many booked months in advance — cancelled at the height of South Africa’s summer vacation period, when up to 1,800 people per day would normally visit the island.

The problems started when Robben Island Museum, which is responsible for the UN World Heritage Site, refused to renew the contract in October of the company that used to operate two high-speed catamarans for the seven-mile trip.

Paul Langa, the museum’s chief executive officer, said the government had decided instead to build and operate its own ferries in order to cut costs and allow for more flexible boat schedules. In the interim, he said, it was using four ageing ferries, which transported prison staff in the apartheid era.

One of these is undergoing maintenance work. Another one developed mechanical problems December 28. Problems were compounded by bad weather the following day that forced the cancellation of all services, Langa told The Associated Press.

“We really are very sorry. But it’s beyond our control,” said Langa, himself a former political prisoner.

He said that officials were trying to squeeze extra passengers on boats that would normally carry staff, and were trying to prioritise foreign tourists on a once-in-a lifetime trip.

He said yesterday that it had been decided to run the outward bound ferries until 5 p.m., rather than 3 p.m.

Bekithemba Langalibalele of Cape Town Routes Unlimited, the public-private partnership tourist board, said one possible solution would be to contract an extra vessel. But Langa said this should not be necessary if all went according to plan.

“All the good that Robben Island does for South Africa’s reputation is being undone by the frustration of trying to get there,” fumed British visitor Ian Carmichael, who paid for tickets for himself and three friends in October.

The group’s 10 a.m. ferry was cancelled but they considered themselves lucky to find place on the 2 p.m. one — until they realised that, too, had been cancelled.

More than 300,000 people per year visit Robben Island, where Mandela was imprisoned from 1965 to 1982. Tours, most led by former prisoners, include his cell, the exercise yard and the quarry where inmates toiled.

Visitors learn how the light in each cell burned all day and all night, how ‘African’ prisoners were given the worst diets and forced to wear shorts, and come face to face with the legacy of racist oppression.