The death toll from a bridge collapse in Indonesian Borneo which hurled dozens of vehicles into a murky river has risen to 11, officials said Monday as authorities probed the cause of the disaster.
More than 30 people are believed to be missing after the 720-metre-long bridge -- built to resemble San Francisco's Golden Gate -- over the Mahakam river collapsed on Saturday.
"The number of people killed were 11," East Kalimantan province's search and rescue agency head Harmoni Adi told reporters.
National Disaster Management Agency spokesman Sutopo Purwo Nugroho, who earlier put the toll at 10, said that bodies were washing up on the river banks.
"Thirty-nine people have been injured and based on reports by the community, at least 33 are missing," he told AFP.
"It's difficult to know exactly how many are missing because we don't know how many vehicles and people fell when the bridge collapsed," he said adding there was "zero visibility" in the river which is up to 40 metres (yards) deep.
Nugroho said rescue teams would use echo-sounding to analyse the position of the bridge's underwater metal frame to ensure it is safe to start removing the debris.
Witnesses reportedly heard a loud crashing sound as the structure buckled, sending a public bus, cars and motorcycles plunging into the broad river in Kutai Kartanegara district.
Survivors desperately swam to the shore, screaming in panic, while others were trapped underwater beneath the debris.
The cause of the collapse was not immediately clear but Nugroho said on Sunday that a steel support cable for the bridge, finished in 2002, snapped as workers were repairing it.
The Jakarta Post daily quoted public works minister Djoko Kirmanto as saying the bridge had been weakened after being struck by boats several times.
"A pillar almost collapsed last year because it was hit by a cargo barge that carried coal," Kirmanto told the daily.
Indonesian President Susilo Bambang Yudhoyono has ordered an investigation into the cause of the accident.
Indonesia is setting a blistering pace of growth, expected to top six percent this year, but investors complain infrastructure is hopelessly inadequate and that the nation is mired in corruption and red tape.
"Around ten to 20 percent of project funds usually go to corruption. The consequence is that building materials are of low quality," said Sri Adiningsih, an economics lecturer at the Gadjah Mada University in Jogjakarta.
The government last year announced plans to spend $140 billion on infrastructure until 2014, more than half of which would have to come from the private sector.
There have been a string of bridge disasters in Indonesia in recent years, including two others this year, according to local newspapers.
Last month, a bridge in South Sumatra province collapsed under the weight of a trailer-truck loaded with construction materials, and in September two workers were killed and four injured when a bridge under construction collapsed in the same province.
Also on Sumatra island, 12 children died in October last year when a suspension bridge collapsed as they were taking part in a traditional ceremony to dispel bad luck.
And in April 2009, one person died and two others were injured when a bridge collapsed in Central Kalimantan province.