A politician has claimed that increasing numbers of South Africans are being killed by bolts of lightning.

Fifteen people were killed in three separate incidents over the New Year weekend, prompting Nomusa Dube, an executive councillor in KwaZulu-Natal province, to call for a government investigation.

South Africa has one of the highest lightning ground strike densities in the world. Figures from the South African weather service show that 28 people died after being struck by lightning between January and November last year.

This was more than double the 12 killed in 2009, while nine died in 2008.

However, it still trailed behind the peak years of 2005 (44 deaths), 1999 (32 deaths) and 2004 (31 deaths).

Seven people in neighbouring houses were killed in a lightning strike in Eshowe, in KwaZulu-Natal, on Sunday. Police said the victims - among them four children - were burned beyond recognition.

In the neighbouring Eastern Cape province, four people were killed and 20 injured when lightning struck a family gathering on New Year's Day. Four more died, also in Eastern Cape, when a commemorative ceremony was hit on the same afternoon.

The incidents were the latest in a series that has included the incineration of a marquee during a party in Ntuthuko village, KwaZulu-Natal, in November.

Severely burnt bodies were still stuck to their plastic chairs when emergency services arrived at the scene. Seven people died, and more than 60 were injured.

Dube, who is the KwaZulu-Natal executive for co-operative governance and traditional affairs, claimed deaths from lightning were a "growing phenomenon" in rural areas. "We will do an investigation with a view of trying to identify the causes of the recent upsurge of fatal lightning incidents in the province," she was quoted as saying in today'sSowetan newspaper. "We will talk to the department of science and technology on what is the cause of the lightning."

Thunderstorms, generating big electrical discharges, are common in South Africa's eastern escarpment between October and March. The South African weather service said the annual average number of lightning-related deaths is 6.3 per million of the population - more than 15 times the global average.

But the greatest concentration of lightning flashes in the world occurs in the tropics, with the highest values recorded over the Democratic Republic of Congo.

William Mfimanga, a forecaster at the weather service, said it was too early to judge whether there had been a rise in lightning strikes or fatalities. "Sometimes people judge it on the amount of damage caused, not the actual statistics," he said. "As a scientist, I cannot draw conclusions just based on reports. Lightning can kill more than five people at a time. As soon as thunder develops, we get lightning, and anything can happen."