Cyclone Phet weakened Sunday after reaching two coastal districts of Pakistan's southern Sindh province, officials said.

Heavy rains and winds lashed Karachi, the province's capital, killing at least four people as the cyclone swirled along Pakistan's coast after killing 15 people in Oman.

"The cyclone moved rapidly eastwards in last six hours and went away from Karachi's coast" after hitting Sindh's Thatta and Badin coastal districts, Qamar-uz-Zaman Chaudhry, of Pakistan's meteorological department, told AFP.

"The cyclone will turn into depression in the next 12 hours, which will result in further widespread rains in Karachi and other coastal parts of Sindh," Chaudry said late Sunday.

Cyclone Phet was earlier expected to landfall near Karachi with maximum winds of 100 kilometres (60 miles) an hour after it hit Oman's coast, where 15 people died, including a Bangladeshi and a Pakistani.

Tens of thousands of people were evacuated from vulnerable coastal villages in Sindh, but thousands more refused to abandon their homes.

Hospitals in the Karachi area were also put on alert and medicines and tinned food stockpiled after meteorologists warned the cyclone might uproot power and communication lines along the coast.

Provincial health minister Saghir Ahmad told AFP at least four people had been electrocuted in Karachi after rains began lashing the city on Saturday night. Such deaths typically occur as a result of fallen power lines or faulty equipment becoming damp.

President Asif Ali Zardari has ordered lawmakers in Sindh to speed up relief work in areas expected to be battered by torrential rains, according to an official statement.

Pakistani authorities have already evacuated 60,000 people from along the 1,000-kilometre coastline, including 23,000 on outlying islands.

Thousands of large advertising billboards along the city streets have been taken down for fear that the winds could blow them over.

Hundreds of relief camps have been established in the affected areas but people have complained about the lack of facilities.

"My family had gone to a relief camp a couple of days ago but there were not enough food and medical facilities which forced us to come back home," Mohammad Hashim, a resident of the Karachi suburb of Rerhi Goth, told AFP.

Nadeem Ahmed, the head of the National Disaster Management Agency (NDMA), said all relevant agencies and the armed forces were on alert.

"We are ready with our maximum abilities and resources to tackle any emergencies," he told AFP.

Chief meteorologist Mohammad Riaz told AFP that 128 millimetres of rain was recorded in the first spell of a cyclone-related downpour late Saturday and that more was expected.

"Heavy rains may cause flash flooding in Karachi and other parts of Sindh and the southwestern Balochistan province," he said.

The government has established relief camps in school buildings and set up health units and control rooms ready to operate if needed, an official said.

A government official in Balochistan province, Ataullah Mengal, said cyclone-related rains had injured 18 people in the coastal areas but no deaths had been reported.