UPDATE 8-Oil rig helicopter crashes off Norway coast, 13 presumed dead
* Helicopter was returning to land from oil platform
* Witnesses say rotor detached while still in the air
* Norway, Britain impose temporary flight ban
* Norway's Statoil halts Gullfaks B oil production
* Black boxes recovered, to be sent to UK for analysis (Adds worldwide grounding for passenger flights, context)
By Stine Jacobsen and Ole Petter Skonnord
OSLO, April 29 (Reuters) - A helicopter ferrying passengers from a Norwegian oil platform crashed in the North Sea on Friday, apparently killing all 13 people on board, rescue officials said.
The 11 passengers and two crew on the flight from the Gullfaks B oil platform, operated by Norway's Statoil, were all Norwegian except for one British and one Italian national, according to the Rescue Coordination Centre for Southern Norway.
"The helicopter is completely destroyed," it said. After several hours searching for survivors, 11 bodies were found and the remaining two people were presumed dead. Continued...