Labour has been left humiliated after being forced to ask a security company it had pledged to boycott to help police its annual conference - only to be rejected.

G4S, which has provided security at the event for 20 years, is understood to be concerned about staff safety after Labour voted for a boycott over its prison contracts and links to Israel.

It follows a warning from Len McCluskey, the Unite boss, that the conference could be cancelled unless a provider is found urgently.

Sources close to the company warned that the short notice it was given and previous incidents at the event, including staff being spat at and verbally abused, made it impossible for G4S to accept the offer.