A letter was sent to staff yesterday saying the trust expected a shortfall in its income of pounds 4m in the current financial year.
In a press statement, the hospital said that some job losses might 'have to be lost through compulsory redundancies. The loss of posts will be applied across all departments and will include all types of staff'.
It also emerged that some wards may close. The number of bed closures has not been finalised.
Harriet Harman, Labour's health spokeswoman, said all hospitals were growing weaker and dismissed Patient's Charter promises as 'hollow'.
A political row erupted last year when two other hospital trusts - Guy's in London, and Bradford - announced big job cuts soon after becoming self-governing.
The Royal London - which says between 400 and 600 jobs must go - became a self-governing trust at the same time.
Including the Royal London Whitechapel, Royal London Mile End and the St Clements psychiatric unit, the trust serves the deprived multi-racial community of Tower Hamlets in the East End.
The hospital said: 'The trust has not secured contracts with district health authorities for all the activity which the trust has the capacity to undertake.
'Any surplus capacity has to be reduced now that the financial position is clear.'
Primary care, maternity, mental health and learning difficulties services would be protected, but costs within general hospital services reduced. Hospital chiefs admitted earlier this year that cuts were being made to try to avoid big losses. They had inherited an pounds 800,000 debt, which was growing, despite a range of cost-cutting measures.
In April, Guy's trust announced 600 job cuts to save pounds 6.8m, and Bradford trust in West Yorkshire announced 300 jobs would go to save pounds 7m.
Ms Harman said: 'Promises to patients in the Patient's Charter are hollow if services are being cut. The problem is not that some hospitals will close and some will grow stronger.
'The problem is that all are growing weaker. Because of insecurity they are all cutting corners, cutting costs and cutting services. The end result will be that we will see more and more people forced into the private sector because they cannot bear the pain of waiting.'
Ms Harman went on: 'The Government has told all hospitals to act like businesses. As a result of that they are all being undermined and are cutting back and being destabilised with services under threat.'
Peter Marshall, east London regional secretary of the health workers' union Cohse, said: 'This appalling news is a direct result of the introduction of untrammelled market forces into the health service.
'It is a scandal that trained health staff will lose their jobs and services will be cut in one of the poorest areas of London.'
Peter Skyte, regional officer for the Manufacturing Science and Finance Union, which represents professional and technical staff at the hospital, said the announcement 'exposes the naked truth of the Government's market force approach to the National Health Service in the 1990s'.