Streets have been submerged and electricity cut off in most parts of Jeddah [Reuters]

At least four people have reportedly been killed after heavy rainfall submerged streets and cut off electricity in parts of Saudi Arabia's second largest city Jeddah.

Cars floated in streets turned into rivers on Wednesday, while putrid odours filled the air as sewage from underground tanks overflowed and mixed with flood water in the Red Sea port of four million people which has no sewage system.

The situation has raised fears of a repeat of floods in 2009 which killed more than 120 people.

Boats and helicopters searched flooded areas and residents said many people were unable to leave schools and workplaces.

Saudi Arabia's King Abdullah ordered rescue operations to be stepped up, warning "anyone who may delay this order", state media said.

"The order is to be implemented now without delay, to provide aid to minimise this damage, especially since the rain is expected to continue for days".

Authorities urged residents to stay indoors but gave no immediate assessment of damage or casualties.

"We are flooded. It's bad. The whole first floor of my house is filled with water and one of my couches is floating in the living room," one woman in Jeddah told Reuters news agency.

"Why weren't we warned about this? There are helicopters rescuing people and cars floating in the streets."

Another Jeddah resident said: "I really don't mind having my house flushed with water. I love rain. But I hate sewage and this is what we are dealing with. I can't stay in my flooded house. This is all diseased water."

Until recently, Jeddah's waste water was dumped in an area in the middle of the desert, which later developed into a large lake dubbed "musk lake" by locals because of its odour.

Only when the lake, which was equivalent in size to 340 soccer fields, had risen to 12m high did Abdullah order authorities to get rid of it.

He also said after the last floods that officials would be held responsible.

Now municipality officials say the lake is empty and water waste is purified and used to water plants in the city.

Source: Agencies