Controversial Tower Hamlets mayor Lutfur Rahman has been told to expect "proper scrutiny" following the results of a by-election.
Labour won two seats and the Conservatives gained one seat in the delayed poll in the Blackwall and Cubitt Town ward. The vote was postponed from May when a candidate died just days before the main London borough elections.
The result means:
- Labour has 22 seats on the council
- Rahman's Tower Hamlets First party has 18
- Tories have 5 seats
Tower Hamlets is one of four London boroughs run by a directly elected mayor instead of the largest party.
Conservative group leader Councillor Peter Golds say he would be talking to Labour councillors about co-operating in a bid to hold Rahman to account.
There was a big police presence at polling stations yesterday following claims of voter intimidation on election day in May and a chaotic count which lasted 23 hours.
Cllr Golds added: