Sister Jacinta Bracken, originally from Ballacolla in Co Laois, disappeared from her convent in Swansea on 19 May 1979, sparking off a major international search by Welsh police and gardai.

The nun left Stella Maris Convent to go shopping for her widowed mother's birthday present. An unconfirmed sighting of the 38-year-old woman was later made at the nearby St David's Catholic church, where it is believed she may have been praying, but she was never seen again.

A new probe under the command of a leading Swansea police officer, detective inspector Andy Hughes, hopes to get closer to finding out the final movements of the missing woman.

Jenny Brain, a former detective for Swansea police who was in the enquiry team from the beginning, described the case as one of the most unusual she had ever come across.

"I was in daily contact with the convent and everyone I talked to just could not believe that Jacinta would leave without telling anyone. . . She had a very close relationship with her family and since that day she has never contacted anyone."

The nun's handbag was found on the foreshore of the seaside town the next day by a local boatman about 30 feet from the West Pier. A subaquatic search was carried out but nothing was ever found. Police had no reason to suspect suicide, nor were any personal effects washed back onto the beach.

Initially, it was thought Sister Jacinta may have gone back to Ireland, police said.

Later examinations found that all her belongings were still in the convent, which included her sailing ticket, money and personal belongings.

Despite an intensive police investigation and a high-profile media appeal, the Irish nun was never seen again.

"This case will be remembered by the people in Swansea for a long time, " the former police detective said.

"Recent police enquiries have also confirmed that no passport was issued and no death was registered under her name in the last 27 years."