The Sunday Mirror stated the Tottenham right-back had inhaled nitrous oxide when out with friends over the summer, alongside photographs of Walker breathing out of a black balloon.
The 23-year-old, who played for England against Moldova on Friday and is in the squad to face Ukraine on Tuesday, wrote on his official Twitter page: “Apologies for not commenting sooner on a story about me today. I’ve been training and am focused on Tuesday’s game for England.
“Now I know the health risks, it was poor judgement on my part.
“I won’t be doing this again and hope that no one else is influenced into putting their health at risk by my actions.”
Walker was named as the PFA’s Young Player of the Year in 2012 and has won seven caps for England since making his debut against Spain in 2011.