Newcastle's Leon Best and Stephen Ireland have issued an apology to the club and its supporters after being pictured at the Tup Tup Palace nightclub in the city on Friday evening.
The pair had been ruled out of Saturday's game at Stoke, which Newcastle lost 4-0, but accept going to a bar was "inappropriate".
A statement released through the club read: "Although we had both been ruled out of the game at Stoke and didn't travel with the team, we realise that going out to a bar was inappropriate ahead of Saturday's game and we fully regret doing so.
"We were asked to have our photograph taken and we removed our shirts as a tongue-in-cheek joke between friends, but of course the resulting coverage in the press suggests a far different night out.
"Whilst our actions were wrong, neither of us had consumed alcohol and we were out for only a very short period of time.
"However, with the team having an important game at Stoke the following day, we should never have put ourselves or the club in that position."
The Newcastle manager, Alan Pardew, was asked about the incident after Saturday's game and said: "That is a situation I have to look at on Monday morning. It is news to me. It is not an ideal situation when you have a game on Saturday, even though they are injured. I will look at that."