British forces help stricken Canadian sub.
HM Naval Base Clyde at Faslane confirmed three crew members were injured.
A spokeswoman for the base said, 'She has suffered an electrical fire on board which has resulted in smoke throughout the vessel.
'She is now on the surface and everything appears to be all right.
'There are three casualties with smoke inhalation, but nothing life-threatening.
It is understood there are about 50 personnel on board the submarine.
The Ministry of Defence confirmed an RAF Nimrod from Kinloss was in the area, while a Royal Navy search and rescue helicopter was launched from Prestwick.
The Victoria-class submarine was formerly named HMS Upholder.
But it was renamed and handed over to the Canadian navy during a ceremony at Faslane on Saturday.
The vessel had been due to arrive in Halifax, on the east coast of Canada, on October 18.
Neil Smith, the Royal Navy's regional director of communication, said, 'We have dispatched a Royal Navy Sea King from HMS Gannet near Prestwick in Ayrshire.
'We have also turned round the Royal Fleet Auxiliary Wave Knight which was in the area. It is a 200- metre fleet replenishment vessel.
'We are scrambling HMS Montrose which is a type 23 frigate which will leave HMS Clyde at Faslane.
'I have to stress that this is a non-nuclear submarine and is powered by diesel electric motors and it was built in the early 90s.'
A spokeswoman for HM Naval Base Clyde said it was too early to establish if HMCS Chicoutimi will be able to continue her journey.
Depending on the extent of the smoke damage, all non-essential crew may have to be evacuated from the vessel, the spokeswoman said.
A Canadian Forces spokeswoman said,
'The crew is safe. Three sailors experienced smoke inhalation but do not require evacuation.'