A woman whose brother was murdered and secretly buried by the IRA has said US President Joe Biden should be told about the "horrible limbo" facing the families of the so-called Disappeared.

Mr Biden is due to visit Northern Ireland this month to mark 25 years since the Good Friday peace agreement.

Dympna Kerr said he had to know about what she described as the "unfinished business" of the peace process.

Her brother Columba McVeigh is one of the four remaining Disappeared cases.

The 19-year-old from Donaghmore in County Tyrone was abducted and murdered by the IRA in November 1975 and his body has never been found.

The search for his remains resumes on Monday at Bragan Bog in County Monaghan in the Republic of Ireland.

His sister said that her family hoped he would be found this time.

But she added: "Those hopes have been dashed so many times before that there still is that gnawing feeling in the pit of my stomach.

"Please make it this time."

• Timeline: The Disappeared and the attempts to find them

The remains of 13 of the 17 so-called Disappeared have been found by investigators.

But four cases remain unsolved - they are Mr McVeigh, Joe Lynskey, Seamus Maguire and Army officer Robert Nairac.

The Provisional IRA has admitted responsibility for 13 of the murders and the Irish National Liberation Army (INLA) said it carried out one.

Ms Kerr said that the US president should be made aware of the plight of the families that had yet to find their murdered relatives.

"President Biden will rightly be proud of the role played by the USA in our peace process and President [Bill] Clinton did so much for the families of the Disappeared," she said.

"But President Biden needs to know that there is unfinished business.

"There are Irishmen and women who every day and every night still have to live in this horrible limbo.

"It has to end."

It is understood that Mr Biden's visit to Northern Ireland will begin in Belfast on 11 April.

The search for Mr McVeigh is being carried out by the Independent Commission for the Location of Victims' Remains (ICLVR).

It was looking for him in Bragan Bog last autumn but the search was put on hold when bad weather set in and the bog became too dangerous to work on.

Ahead of the resumption of the search on Monday, the ICLVR's lead investigator Jon Hill said: "If the remains of Columba are in this part of the bog we will find them.

"If we have to clear a section of the forest then we'll do it."

He appealed for anyone with information about Mr McVeigh's disappearance to contact the commission.

"Any information that comes to us is treated in the strictest confidence and will never be used for any other purpose than to find the remains and return them to their family," he said.