Health Secretary Andrew Lansley said that past efforts to tackle the deficit at the South London Healthcare Trust had not been successful, and that turning its fortunes around would be a "big challenge".
It is the first NHS trust in the country to be put under the control of a special administrator.
"Although there have been some improvements in mortality rates, maternity services and infection control, and some early signs of improvements in waiting times, they do not go far enough. It will be impossible for South London to build on these improvements while tackling such a large deficit....
"...I am confident that with the regime I am enacting today in place, and working extensively with clinicians, health service leaders, patients and local people, [the special administrator] will have the tools and framework in place to find a long-term satisfactory solution for the people of south east London."
More top news
The London Mayor insisted he was "not saying that nationalists are somehow racist or bigoted" after outraging SNP supporters.
The teenagers, aged 19 to 15, appeared in custody at Westminster Magistrates' Court on Saturday, supported by their families.
Parker Dairies moves home after 120 years on Wood Street in Walthamstow