The local authority with the highest level of youth unemployment in the UK has proposed scrapping its Connexions contract before a replacement careers advice service has been created.
Nearly 36 per cent of 16 to 24-year-olds in Lewisham were out of work last year, according to figures from the Office for National Statistics.
But the south London borough's elected mayor, Sir Steve Bullock, was last night considering a recommendation to save pound;1.5 million by ending its contract with the company which provides its Connexions youth advice service.
Instead the council will expect schools and colleges to give careers advice to their students, while it retains a pound;1.2 million service focusing solely on unemployed teenagers who have given up studying.
The cut would be the largest yet made to a local Connexions service, which has seen its Government grant fall by over 20 per cent. While some local authorities have cut as many as half of Connexions jobs, Lewisham is believed to be the first to have considered withdrawing all support.
Unison, which represents 15,000 Connexions staff, said it was considering legal action against local authorities which risk failing to provide independent careers advice for students or support for teenagers not in employment, education or training (Neet).
The union estimates that some 8,000 jobs are at risk. It said local authorities should wait to see the plans for an all-age careers service, due in September, before dismantling the current system.
A spokeswoman said: "We are looking very seriously at where there may be opportunities for us to make challenges to councils that are making cuts in Connexions services.
"Lewisham is an area where there is very high youth unemployment and they have decided not to renew their contract after 31 March without setting out what the alternative arrangements will be. They seem to be pinning their hopes that schools and colleges will be able to continue the advice."
Unison is investigating the possibility of a judicial review in the summer, involving councils which it believes may not be fulfilling their duty to provide independent advice for teenagers considering post-GCSE career or education options.
Council papers show that Lewisham believes it will meet its statutory obligations by providing a "comparable" level of resources for vulnerable groups with support from a key worker, and using youth workers to try to prevent students becoming Neet.
Under-19s, or under-24s with learning disabilities, will continue to have access to a personal adviser, the council said.
And it intends to continue its own eight-week programme for Neets, which involves presentation and interview training, personal development, volunteering and an Outward Bound course.
A Lewisham Council spokeswoman said the authority had no choice but to axe Connexions.
"The Government has announced that it intends to establish an all-age careers service," she said. "Funds which were provided to the council for this purpose have been significantly reduced.
"The council will need to focus its available resources on the most vulnerable young people including those with SEN; that is, reducing the number of young people who are not in employment, education or training in the borough."