South African officials say 28 suspected poachers were arrested in April in the country's main wildlife park, a sharp increase over the detention rate of previous months.

Paul Daphne, a spokesman for South Africa's parks service, on Friday attributed the increase in arrests in Kruger National Park to the effectiveness of new anti-poaching helicopters as well as sniffer dogs that track intruders.

Daphne says Kruger rangers have four helicopters, including two donated by American philanthropist Howard Buffett.

He says a total of 62 suspected poachers have been arrested in the park so far this year. At the same time, he says, more poachers are entering the park.

Poachers killed more than 1,200 rhinos in South Africa in 2014 to meet demand for rhino horn in parts of Asia.