A HALLOWEEN style plastic arm sparked a major police operation off the M62 yesterday, disrupting thousands of motorists.

The drama, complete with a helicopter and police dogs, was caused by a joke shop forearm with fake blood.

Police said last night that it may have even fallen from a passing lorry or car.

The saga began when members of the public reported seeing a severed arm lying on an exit sliproad, prompting police to scramble the force helicopter.

The slip road approaching Tarbock Island at junction 6 was shut down for four hours while scientific support officers scoured the verge with police dogs as the chopper roared overhead.

The slasher movie style arm was discovered by a couple of council workers on the carriageway and the road was re-opened by 4.30pm.

A spokesman for Merseyside Police confirmed last night that the plastic arm was of the Halloween variety and not a prosthetic limb.

Detective Inspector Tom Keaton, from Knowsley CID, said: "This was treated as a major investigation that tied up large amounts of resources.”