Government inspectors have been sent in to Tower Hamlets council for the second time in a decade amid concerns about how the borough is being run.
The Government said it is uneasy about a range of issues in the local authority, including the "independence" of the returning officer, who oversees elections, and the expansion of Mayor Lutfur Rahman's office.
Inspectors have also been asked to look at scrutiny, financial planning, staff appointments and grant allocations.
There has been a "significant churn" of senior officers at the council since Mr Rahman won back control of the borough with his Aspire party in 2022, Department of Levelling up, Housing and Communities (DLUHC) officials said.
In a letter to Tower Hamlets chief executive Stephen Halsey, deputy director of local government stewardship, Maxwell Soule said: "Given our concerns relate to broad decision-making, and whether the standards expected for effective and convenient local government are being upheld, the inspection will consider decision-making in relation to those functions, encompassing leadership, governance, organisational culture, use of resources and impact on service delivery.
"The Department is concerned with your authority’s ability to comply with its Best Value Duty."
The borough was subject to intervention from Government inspectors between December 2014 and September 2018, following Mr Rahman's first term as mayor.
Ex Newham chief executive Kim Bromley-Derry has been appointed to lead the latest investigation.
He was banned from standing for office for five years. In 2022 he was reelected as the borough's leader along with 24 Aspire councillors.
A Tower Hamlets council spokesman said: “We are surprised by the decision however it is of course the prerogative of the government and we are confident in our work and will cooperate fully.
“Our work has been praised in recent independent reviews by the Local Government Association Peer Review and Investors in People. Although both reviews were positive, we are already delivering action plans to fulfil their recommendations for further improvement as is the culture in our council.
“In recent months, the council has also made significant progress in resolving historic financial issues of audit, assurance and governance going back to 2016. Accounts for financial years 16/17, 17/18, 18/19 and 19/20 have all been signed off by independent auditors.
"Tower Hamlets has delivered innovative measures to improve more lives such as being the only local authority to provide free school meals for all primary and secondary schools. An achievement recognised with an award by a cross party parliamentary group only last month.”
Tower Hamlets Labour councillor, Marc Francis, said: “It is no surprise to us as opposition councillors to see that civil servants have ordered this best value inspection.
“We have been warning about this situation for more than a year, including by debating the woeful ‘action plan’ put forward following stinging criticism by the recent LGA Peer Review.
“The Mayor and Aspire councillors have made it clear they haven’t changed their ways.”