NHS Lothian has pledged to continue to provide education and outreach sexual health services to young people after terminating its contract with a charity which has provided them for 45 years.

Caledonia Youth (CY), formerly the Brooke Advisory Service in Scotland, alerted partner agencies that it had lost the work in a letter earlier this month.

Chief Executive Hawys Kilday told partners that she was "greatly disappointed" that NHS Lothian had chosen to end its relationship with Caledonia Youth, but said staff would soon be unable to accept new referrals, with NHS Lothian due to take over the service in April 2014.

The Edinburgh-based relationships and sexual health service for young people in Scotland had been in talks with NHS Lothian's Sexual Health, Blood-Borne Viruses and Substance Misuse team since August 2012 and had been told there would be an opportunity to tender for the service.

However the health board now intends to take sexual health clinical services for young people in house, to the purpose-built Chalmers Sexual Health Centre, which it opened in 2011.

In the letter to partners Ms Kilday expressed concerns that the centre would intimidate some young people who previously came to the CY clinic via education and one-to-one support sessions.

"Many young people access our clinic having first learned about services via educational interventions," she said. "Many more steer away from places where their paths may cross with adults - parents, teachers, family friends and the like. Vulnerable groups are even more challenged, when accessing services."

While the Chalmers Centre will be providing clinical services, it is not clear what will happen to the education side of CY's work, its head said. "Education and one to one support are all integral to making a difference where prevention is concerned."

Meanwhile Ms Kilday warned that careful work with young people in a sensitive area could put pressure on NHS Lothian's staff, who are still referring clients to CY services, and who will need to manage hundreds of extra consultations a week with young people, she added: "[these are] consultations that often take far longer than that of an adult, due to their more complex nature". The transfer of skilled CY staff to the centre under TUPE protections is expected to help the Chalmers Centre absorb the work.

A transition period is now under way with CY continuing to provide services under its current contract, which was extended at the end of April until March 2014.

"We will be working closely with [the Chalmers team] to ensure a smooth transition for our young clients," Ms Kilday said.

A Caledonia Youth spokesperson said: "While we are obviously disappointed that NHS Lothian has chosen to end its contractual relationship with us after such a long period, we remain very confident about the direction of travel Caledonia Youth is now taking.

She said winning support from the Third Sector Early Intervention Fund earlier this year, had also allowed CY to develop new work.

This includes a prison project currently operating in four Scottish Prison Service establishments, and which the charity hopes to roll out to more jails in the coming months.

"We fully understand the fact that NHS Lothian has invested heavily in Chalmers, a new resource that needs to be fully utilised," she added.

Alex McMahon, Director of Strategic Planning at NHS Lothian, said: "Following a comprehensive review of sexual health services across Lothian, we have made the decision to increase the provision and resources for young people's sexual health and wellbeing and to run the service from the Chalmers centre."

As a purpose built sexual health centre, Chalmers will provide improved access to the full range of contraception and sexual health screening, treatment and care, she said.

"While we appreciate that the decision to remove funding from Caledonia Youth is difficult for the organisation, we believe that moving the services to Chalmers provides the best service for young people in Edinburgh.

"We have had a long and productive relationship with Caledonia Youth and I would like to thank the team there for all their good work over the years.

"We will be exploring with the team the opportunities for TUPE and will continue to work in partnership with Caledonia Youth to identify ways to improve the sexual health and wellbeing of our young people."