HONG KONG (AFP) - Hundreds of passengers were locked inside a grounded Dragonair plane overnight when a massive storm prevented their landing in Hong Kong, the airline's parent company confirmed on Monday.

Flight KA875 took off from Shanghai at 6.30pm local time on Sunday with 252 passengers on board but was diverted to nearby Shenzhen airport when Hong Kong was deluged by rain and hail.

A power failure stopped the flight from continuing on to its intended destination when conditions improved, and passengers were forced to stay on the tarmac for seven hours, a spokeswoman for Cathay Pacific, which owns Dragonair, told AFP.

"The initial plan was to re-depart to Hong Kong as soon as the weather condition allowed... regrettably, the delay was further extended when there were technical problems with the aircraft's auxiliary power unit," the spokeswoman said in a written statement.

"We sincerely apologise that as Shenzhen is not an operating port for Dragonair, the deplaning process (took) longer than expected because of constraints in local ground handling and immigration clearance," she said.

The stranded passengers were left with little food and water, leading some to shout at the flight crew while others were restrained from leaving by attendants guarding the cabin door, the South China Morning Post reported.

A "special clearance" was obtained on Monday morning to let passengers alight, some 11 hours after departure.

Sunday's storm saw Hong Kong authorities issue a "black" rainstorm warning, the highest possible level, advising residents to shelter indoors and refrain from all travel.

Authorities received dozens of reports of landslides and flooding.

More than 500 flights have been delayed since the storm began, according to the city's Airport Authority.

Shenzhen airport's management could not be reached for comment.