Five Japanese scuba divers were found alive Monday clinging to a coral reef in rough waters off the Indonesian resort island of Bali three days after they went missing, officials said.

Fishermen spotted the divers, among seven women who went missing Friday, some 20 kilometres (12 miles) from where they set off for a diving expedition but could not rescue them because the waves were too high.

But one of them was later rescued by a helicopter, which also dropped food to the stranded divers. The four others were being picked up by a rescue boat and would be taken to Semawang beach in southern Bali.

"There were five found atop a large coral reef," Rudi Tjandi, an official from the Bali disaster agency, told AFP.

"The waves and current were quite strong, so the fishermen who spotted them couldn't approach."

He said they were found at Manta Point off the west coast of Nusa Penida island, just east of Bali.

They had set off on a dive expedition Friday from the Mangrove area of Nusa Lembongan, an adjacent island. The shortest route to where they ended up was around 20 kilometres.

Local police chief Nyoman Suarsika also said that they were found in the Manta Point area.

Officials had no news of the other two missing divers.

At Semawang beach a group of 20 Japanese people, including relatives of those missing, were seen sitting at a restaurant. One woman was crying and the others refused to be interviewed, an AFP journalist at the scene said.

Four ambulances were waiting next to the beach for the divers to arrive, while dozens of Balinese people had also gathered.

A search involving about 100 people has been under way since the divers' disappearance, with rescue efforts hampered by heavy rain and strong winds earlier Monday.

'Praying for her safety'

"I'm praying for her safety," the mother of missing instructor Shoko Takahashi told reporters in Japan on Sunday before leaving for Bali, according to the Yomiuri Shimbun daily.

"She is an active person with a dependable personality. She never does foolhardy things."

Takahashi and her husband had set up the operator known as Yellow Scuba that took the divers out on the trip, said Japanese consular official Kenichi Takeyama.

Takeyama said Yellow Scuba had provided boats and staff for the search.

The women were experienced scuba divers who had logged more than 50 dives each.

The dive boat's skipper said he was following the divers for some 20 minutes before a sudden downpour made the water cloudy, according to Japan's Asahi Shimbun newspaper.

He moved his 10-metre-long boat to a point some hundreds of metres (yards) away where the divers were expected to resurface at an agreed time, the report said.

When they failed to resurface, the skipper said he searched for them for an hour before reporting the incident.

But Bali province search and rescue chief Didi Hamzar told reporters on Sunday he had received information that the skipper had run out of fuel at some point, and had to refuel before heading to the agreed meeting spot.

John Chapman, a Briton who runs the World Diving Lembongan operation on the island where the women went missing, said the heavy rain and choppy sea could have been a factor in their disappearance.

He said a sudden downpour would have made some safety procedures, such as meeting at a brightly marked buoy, difficult because of poor visibility.

To assist rescue officials, Chapman on Sunday conducted a dive to simulate the group's, saying the current was "quite gentle" but became much rougher when he surfaced.

Japan's Kyodo news agency said the missing women were named by police and rescue authorities as: Ritsuko Miyata, 59, Emi Yamamoto, 33, Nahomi Tomita, 28, Aya Morizono, 27, Atsumi Yoshinobe, 29, Shoko Takahashi, 29, and Saori Furukawa, 27.