West Ham United manager Sam Allardyce says Andy Carroll's prolonged absence through injury is a "great worry" and accepts he is not sure when the striker will be ready to return.

Carroll hasn’t made an appearance for the Hammers this season following his permanent move from Liverpool as heel injuries have extended his comeback.

"We've been trying to get a date out of the guys over in Amsterdam," Allardyce told Sky Sports News.

"But they're reluctant to give us any clear indication of just how long it's going to be before he can join us back here and start training with the players, with the squad and then obviously getting into the team to play some games.

"It's obviously a great worry and concern for us all and one we haven't expected, but one we have to make sure we deal with."