Liverpool boss Jürgen Klopp says Daniel Sturridge will be unavailable for Sunday's visit of West Ham United as well as next week's Premier League clash with Middlesbrough.

The striker has missed the Reds' last three games - wins over Sunderland and Leeds United and last weekend's defeat to Bournemouth - with an issue concerning tightness in his calf, but finally returned to training on Friday.

Though the England international re-joined his teammates on the training pitches at their Melwood training ground, Klopp is reluctant to name an exact return date for Sturridge.

Klopp unable to issue return date on striker

The manager, asked at his pre-match press conference ahead of this weekend's clash with West Ham, insisted that they have "no real idea" of when Sturridge will be back.

"Until now he didn't train on the pitch, maybe today but it wasn't 100 per-cent clear yesterday [whether he would return]," Klopp told reporters.

He stated that the No.15 will "go out today on the pitch" to train, but only with the club's "the rehab coach" rather than "starting the football work" with his teammates.

The German added that he has "no idea when he is back" on Sturridge and declared that there is no need to put a timeline on when the striker will be back in contention for the starting eleven.

He said that he "learned pretty early" during his time on Merseyside that he should avoid making pressure "by making timelines" and continued: "So why should I do it? He will be back as quickly as possible, but I've no idea at this moment."

Klopp said that, as he is "not training with the team at the moment" then Liverpool "don't have to think about him for West Ham" or "think about him for Middlesbrough" the following Wednesday.

He suggested that the 27-year-old could "maybe" come back into the fold after that, but reiterated that he "really" has "no idea" when he will be back although "it would be nice" to have him back for the Merseyside Derby against Everton on 17 December.

Manager says Reds can't force Sturridge return

The Reds boss also said that there is nothing he can do to aid Sturridge's comeback, insisting that patience is required.

He said that he can only "wait" and called it his job to do so, acknowledging that the striker is "not happy" but accepting: "That's the life of football. You cannot force things. Never."

Klopp added that even "the name of the player or the quality of the player" has no importance and no bearing on the decision, saying that rather "as a manager" he must wait "until they're back" when it comes to injured players.

He continued that sometimes he and his staff "have to wait a little bit longer" because it can be decided, with Klopp noting that they have done so before, that a recovering players needs "a few days' training" before they "start again."

Klopp accepted: "It's not perfect in our situation with Phil [Coutinho] and Danny [both out injured], but we cannot change it."