The anti-bullying charity BeatBullying is to call in administrators because of "significant financial difficulties".
The charity last week replaced its website with a message saying that its services were down and directing people in need of support to Samaritans or ChildLine.
A source close to BeatBullying, who asked not to be named, said that the charity’s staff and arm’s-length contractors, such as counsellors and website moderators, had been receiving only half pay since August.
The source said that the charity’s offices in Crystal Palace, south-east London, were locked last week.
A statement today from the trustees of BeatBullying said that the charity had "for some time faced a challenging financial environment. The nature of this challenge has recently become acute, resulting in the charity facing significant financial difficulties."
It said that the charity last week filed a notice of its intention to appoint administrators to protect itself from creditor action while options could be explored.
"Prior to and during this period, the trustees, with both legal and financial support, have been engaged in intensive discussion and negotiation with a number of third parties, the outcome of which will enable us to identify the best way forward for the BeatBullying Group, its creditors, employees and service users," the statement said.
"The trustees have now resolved to appoint an administrator to take forward these discussions.
"This is clearly a difficult time for anybody connected with the BeatBullying Group, particularly the people who have come to depend upon the services and support that they have received. Our aim is to resolve this difficult situation as soon as possible and to the fullest extent we can given the difficulties faced by BeatBullying, in the best interests of its creditors and staff. In the meantime, we would like to thank the supporters, staff and advisers who continue to work with us."
An online counselling service for young people provided through the BeatBullying website was pulled without warning when the website went down last week, the BeatBullying source said.
This was "very unethical practice", the source said.
The charity’s most recent set of accounts show that it made a loss of £280,065 on an income of slightly less than £2.4m in 2012. Its income for 2012 was down by £187,739 on the previous year.
Its entry on the Charity Commission website says that it has 44 employees, and more than 5,400 volunteers.
BeatBullying was founded in 1999 by Emma-Jane Cross, who remains its chief executive, and was registered as a charity in 2003.
The Cabinet Office last year gave a £500,000 grant to the charity to expand Mindfull, its online mental health service for children and young people.