York council leader Chris Steward has been taken ill and his deputy has stepped in to cover his duties.
Liberal Democrat Cllr Keith Aspden, deputy leader of the council, took over the duties of his Conservative coalition partner Cllr Steward after he fell ill.
A City of York Council spokesperson said:
Cllr Steward, 36, the member for Rural West York Ward, has led York council for almost exactly a year. The local elections on May 8, 2015, left Labour with 15 seats, the Conservatives with 14 and the Lib Dems with 12.
A few days later the coalition between the Conservatives and Lib Dems took control with Cllr Steward appointed leader.
He has been Conservative group leader since taking over from Cllr Ian Gillies when he became Lord Mayor in 2014.