Paul Lambert’s future as Stoke City manager is uncertain after it emerged he has a break clause in his contract that either he or Stoke can activate by the end of June, it can be revealed.

Stoke were relegated from the Premier League on Saturday, with Lambert unable to halt the club’s drop into the Championship after taking over in January. And his future as manager for next season ahead of talks with the club’s hierarchy later this month is now unclear because of the clause.

Stoke are expected to thrash out their plans for the summer after the final game of the season at Swansea on Sunday. Lambert inserted a similar clause into his contracts at former clubs Blackburn Rovers and Wolverhampton Wanderers.

He has insisted he would be happy to stay at the Bet365 Stadium and rebuild the squad over the summer, with a number of players expected to leave. Stoke chairman Peter Coates has previously admitted that he was pleased with Lambert’s work, after the Scot replaced Mark Hughes in the New Year.

Lambert signed a 2½-year deal and was a surprise appointment after Stoke initially targeted Gary Rowett and Quique Sánchez Flores, while holding talks with the Republic of Ireland manager Martin O’Neill.