Part of an oil rig gave way at a Singapore shipyard on Monday injuring 90 workers, one critically and 22 seriously, in one of the more serious workplace accidents in the wealthy Asian city-state.

The accident happened at Jurong Shipyard, owned by Sembcorp Marine Ltd, the world's second-largest rig builder.

"Preliminary findings indicate that the jackup mechanism of one of the legs of a three-legged jackup rig had failed, causing the rig to tilt to one side," it said. "All work has stopped at the listing rig."

Sembcorp Marine, linked to Singapore state investor Temasek Holdings Pte Ltd, said the accident happened during a test at a rig under construction.

"As investigations are in progress, the company is unable to provide further details at this stage," it said in a statement.

Shares of Sembcorp Marine, whose local rival Keppel Corp Ltd is the world's largest rig builder, ended 2.19 percent lower as the Straits Times Index fell 0.14 percent.

Temasek is a majority shareholder of Sembcorp Industries Ltd , which has a stake of nearly 61 percent in Sembcorp Marine. Temasek also owns 21 percent of Keppel.

Singapore, a global financial centre and home to the world's second-busiest container port, is a major hub for ship and rig repair, conversion and construction and for oil, gas and petrochemicals.

Jurong Shipyard was also the site of Singapore's worst industrial accident, when 76 people were killed in an explosion on the Greek tanker Spyros in October 1978.

In the first half of this year, 26 workers were killed on the job in Singapore, down from 31 in the same period of 2011, the government's Workplace Safety and Health Statistics Report showed in September.

At 246, the number of major workplace injuries was 3 percent lower than in the first half of last year.