A Northern Ireland coroner has said he is still unsure whether a grave exhumed in the search for a missing schoolgirl has no links to her disappearance.

Brian Sherrard said confirmation that remains removed from the Co Sligo grave are not those of Arlene Arkinson had failed to draw a line under the issue, as he suggested the need for tests on other bodies buried in the plot.

"More work needs to be done before I would be content to leave this matter to one side," he told Belfast Coroner's Court.

Arlene, 15, from Castlederg in Co Tyrone, vanished after a night out in Co Donegal in 1994. She was last seen in the company of a convicted child killer, the late Robert Howard.

Howard was always the prime suspect in the Arkinson case.

The Co Sligo grave was exhumed by gardaí in March, almost 20 years after a priest received an anonymous tip-off that a body wrapped in plastic sheeting found buried just below the surface could have been Arlene.

Gravediggers found the body 2ft to 3ft down when opening the grave for another burial in 1996, but subsequently reburied it.

The phone call to the priest came in 1999. He informed gardaí but they did not pursue an exhumation at the time.

Around that time a woman also wrote to a priest to say she had heard that, shortly after Arlene's 1994 disappearance, a man had persuaded some gravediggers to bury her body in a grave they were digging for a conventional burial.

The schoolgirl's family expressed dismay last week when the authorities south of the border said a body exhumed in the Co Sligo graveyard was not Arlene.

There was a further twist at a preliminary hearing in Belfast, when Mr Sherrard was told that the remains examined belonged to an adult male, not a young girl.

The coroner said he had a number of concerns following the revelation.

He said gardaí needed to clarify whether there was an additional body in the grave, other than the four formally registered as being buried there.

The coroner said he also needed to know whether all of the remains found in the plot had been examined, or just one.

"It would be foolhardy if at this stage I was to draw a line under this," he said.

Highlighting that he has no authority to demand information from An Garda Síochána, he asked that Police Service of Northern Ireland officers ask the gardaí for co-operation in "filling in the blanks".

Arkinson family barrister Ivor McAteer described the development as "very peculiar".

"Up until today we weren't aware that body that had been examined was male," he said.

Mr McAteer said the family wanted to know what had prompted gardaí to pursue an exhumation in 2018, given the fact that they had not chosen to do so in 1999 when informed of the telephone tip-off.

He said the family had been upset by how the exhumation had been handled and were mindful of the trauma it was causing relatives with loved ones buried in the Co Sligo grave.

"The Arkinson family are very aware of the distress that the family of the deceased people are enduring and have no wish to trample on their grief and make things worse," he said.

He added: "We are all in the dark about how much relevance this will have to the ultimate inquiry."

Howard died in prison in 2015.

He was acquitted of Arlene's murder by a jury that was unaware of his previous conviction for murdering 14-year-old Hannah Williams, whose body was found in an industrial area close to the Thames Estuary in 2002.

Mr Sherrard has heard the majority of evidence in a long-running inquest but will not deliver his findings until a number of outstanding issues, including around the Co Sligo grave, are resolved.

He scheduled another preliminary hearing for 4 September.