An American expert on primates says Cape Peninsula baboons have become uncontrollable because of "extreme" activists who thwart tested solutions, it was reported on Tuesday.

In an open letter to the Cape Times, professor Shirley Strum slammed relaxed baboon monitoring practices.

"The baboons should have been aversively deterred from approaching and feeding on human food from the start and consistently since the first signs," she said.

"It's a joke to have monitors walking behind clapping hands at this point. I'm not even certain major deterrent efforts will be effective for many troops, but it is the only option now short of eliminating most or all of the baboons."

Strum, who lectures at the University of California, said that after visiting troops around Cape Point and urban areas, she found they had taken baboon "ingenuity and adaptability to the logical extreme".

City biodiversity manager Julia Wood told the newspaper she agreed with Strum, saying some baboons, especially males, had become dangerous.

Wood said their strategy was to keep baboons out of urban areas, with electric fences likely to be the best method.