Services provided by Barts Health NHS Trust at two east London sites have been branded inadequate by the Care Quality Commission.
England’s chief inspector of hospitals Sir Mike Richards issued his damning verdict after reviews at Newham University Hospital and the Royal London Hospital.
Labour London Assembly Member for City and East John Biggs AM has now called for "urgent" Government action.
The trust - the largest in the country serving more than 2million people - had already been placed in special measures following an investigation at Whipps Cross University Hospital, the outcome of which was released in March.
A total of 65 areas of improvement have been identified across the three sites.
Sir Mike said: “It is clear that the leadership issues we found at Whipps Cross were replicated at the other hospitals.
"It is three years since the merger which formed the trust – but there is still a lack of engagement with the staff, low morale, high levels of stress, even confusion among the workforce about who is in charge.
“Across the trust there is too little attention paid to safety, with failures in incident reporting and auditing, and in dealing with or learning from complaints.
"It is worrying that the trust’s directors didn’t seem to have confidence in their own data – a basic requirement in assessing their performance.
"It is all the more of a concern with waiting times which were so long, or that operations were being cancelled.”
Services in the Whitechapel and Newham facilities were inspected for three days by two teams in January.
They concluded the trust “lacked strategy and vision”.
Steve Ryan, chief medical officer at the Barts Health NHS Trust, said: "These CQC reports describe some services that fall short of what we aspire to.
"We are very sorry for the failings identified by the CQC in some of our services at Newham and The Royal London hospitals. We know we have a big challenge ahead but we are determined to rise to that challenge."
Sir Mike said the CQC would continue to work with the NHS Trust Development Authority to support improvement.
He said: “While we have found many individual services require improvement, we also found examples of good services at both Royal London Hospital and Newham.
“We met a very committed workforce who felt undervalued by trust leadership, but valued by their patients and colleagues, and their local managers."
Labour London Assembly Member for City and East John Biggs AM said: “There are obviously serious issues with Barts Trust that need urgent action from Government.
"Whilst the staff at the hospitals are doing an excellent job in tough circumstances, the CQC report identifies worrying concerns about understaffing and the number of cancelled operations at the Royal London and Newham University Hospital.
“Residents in East London need to have confidence that the Government and NHS will take urgent action to increase staffing levels and bring these hospitals up to standard.”
Newham Council's mayoral advisor for adults and health councillor Clive Furness said: “Our residents expect to receive the care they need and deserve.
"This is why the Care Quality Commission’s overall assessment of Newham University Hospital is very disappointing.
“Working with the NHS Newham Clinical Commissioning Group and the Barts Health NHS Trust, I am committed to ensuring that changes are made quickly to ensure all members of the community benefit.”