BEIJING, July 8 (AFP) - A major Chinese tunnel under construction on the Sichuan-Tibet highway has collapsed, killing 12 construction workers, local residents said Tuesday.

The Erlangshan tunnel, a state-level project designed to improve road links between inland China and Tibet, collapsed in two places one near its middle and the other towards its western mouth in the early hours of July 4, residents of the nearby town of Luding said by telephone.

They said the collapse was due to heavy rain storms in the region from the start of July and said 12 workers from the construction company had been killed.

State radio had earlier reported that five were killed, with seven others missing.

The tunnel was scheduled to replace the tortuous Erlangshan pass over the 3,437-metre (11,342-foot) Erlang mountain in the far west of Sichuan province, southwest China.

"The mountain pass was not affected like the tunnel. It is still open and was not influenced by the rains," said one local resident.

Rescue work in the tunnel, which was nearing completion, was at first hampered by a large mudslide which blocked the entrance from the western side, the radio said in its evening news bulletin.