Four senior players – Jonny Evans, Gareth Barry, Jake Livermore, Boaz Myhill – were involved in “an incident” during the club’s mid-winter training trip to Spain.

The Baggies announced on Friday that they have opened an investigation into the matter.

The club say the quartet will be “subject to the full rigours of our internal disciplinary procedures”, and that they will make no further comment until their investigation is completed.

Later in the day, club captain Jonny Evans, midfielders Gareth Barry and Jake Livermore, and reserve goalkeeper Boaz Myhill identified themselves as the players in question, and released a statement on the club website apologising for the incident.

“We would like to take this opportunity to apologise to our team-mates, the Head Coach, the Club and especially the supporters for the events which have been the subject of widespread and negative publicity,” the quartet said.

“We felt it important we identify ourselves as the players involved in an incident which occurred during the training camp in Spain this week out of respect for team-mates who otherwise could be implicated by association.

We freely acknowledge and apologise for the break of curfew which we accept represented a breach of the standards of professionalism required of us as representatives of West Bromwich Albion FC.

The Club has informed us that it will now conduct its own inquiry into the incident and we will co-operate fully.

In the meantime, we would like to assure our supporters that this incident does not reflect the determination and resolve we possess to do all we can to recover a difficult season.”