A British diver has died during maintenance work at an offshore German wind farm in the North Sea, according to officials.

Wind farm operator Alpha Ventus said the 48-year-old was diving at a depth of about 2 metres at a wind turbine's foundation when he apparently suffered a heart attack.

His identity was withheld for privacy reasons.

Alpha said the 12 turbines are 28 miles off the coast and produce electricity for about 50,000 households.

German news agency dapd reported the diver's death was the third deadly incident at German offshore wind farms in two years.

Germany is seeking to multiply wind power generation with new offshore platforms in the North and Baltic Seas, but their construction and operation is logistically challenging.