A club statement said: "The club has discussed the current position in detail with both the PFA (Professional Footballers' Association) and Adam's representatives.

"In line with those discussions we recognise that the player is entitled to re-commence his duties with the club while the legal process continues. He will therefore return to training.

"The club's own investigation cannot continue until the conclusion of the legal process.

"Sunderland AFC will make no further comment on the matter due to the ongoing police investigation."

Durham Police later confirmed that investigation remains "very much live and ongoing" and reiterated its warning to social media users about the dangers of identifying the alleged victims of sexual offences.

A statement said: "Sunderland AFC informed us this morning of their decision, which of course is a matter entirely for the club.

"The police investigation remains very much live and ongoing and a man remains on bail while enquiries continue.

"We would once again urge those posting on social media to be aware of the effects their comments can have.

"We accept rumour and speculation may be inevitable, but many of the comments have been distressing to the complainant, her family and people connected with the investigation."

Former England international Johnson has not played for the club since the 2-0 Premier League defeat by Manchester United on February 28, but could now be in line to make a contribution at West Ham on Saturday.

He was arrested at his County Durham home on March 2 and questioned at Peterlee Police Station before being released on bail until March 18.

However, that period was extended until April 23 on Tuesday.

News of the player's impending return came during another tumultuous week at the Stadium of Light, during which head coach Gus Poyet was shown the door and replaced in the short term by 67-year-old Dutchman Dick Advocaat.

Poyet departed in the wake of Saturday's 4-0 home defeat by Aston Villa, which left Sunderland sitting just a point above the relegation zone with nine games to play.

Advocaat's task is simply to keep the club in the top flight, and the importance of his mission was underlined by financial figures filed on Wednesday which showed increased losses of £16.3m on ordinary activities before tax for the year ended July 31, 2014.

In the report, chairman Ellis Short says: "The directors consider the major risk of the business to be a significant period of absence from the Premier League. Ongoing investment in the playing squad aims to reduce this risk."

Johnson could prove key as Advocaat and his staff attempt to find a way to get the best out of January signing Jermain Defoe.

The 32-year-old striker, who arrived on Wearside from MLS side Toronto in a swap deal with Jozy Altidore, scored twice in his first five appearances for the club but has not found the back of the net in his last five.

Defoe appears to represent Sunderland's best hope of dragging themselves out of trouble, but Poyet simply could not find the system to provide him with the chances he needs, on Saturday opting to play him as a lone frontman with Scotland international Steven Fletcher attempting to provide support from the left wing, a job to which he proved less than suited.

Advocaat will hope Johnson can provide the natural width, pace and flair which won him his big-money move to Manchester City and his 12 England caps to spark the fightback his club needs during the closing weeks of the campaign.