Gardaí investigating the murder of Tina Satchwell have arrested a man in his 50s following the discovery of human remains at a house in Youghal.

The man in his 50s was arrested in the Cork town shortly after the discovery was announced. He is being held at a Cork Garda station.

Gardaí investigating the 45-year-old’s disappearance upgraded their investigation to a murder inquiry on Tuesday, six years after she was last seen.

They began a major search at her home in Cork, bringing in industrial digging equipment and engineering experts.

The search has been ongoing ever since with investigators examining the interior walls, ceilings and floors of the house.

The search also involved a dig of a garden and the dismantling of an area of concrete at the back of the house.

Gardaí outside the house where Tina Satchwell lived in Youghal, County Cork. Image: Jamie O’Hara/Newstalk

This morning, Gardaí confirmed that human skeletal remains have now been discovered.

It's understood officers discovered the remains under the floor of the house this morning.

DNA samples have been taken and Gardaí are seeking to identify the bones by cross-referencing the sample against their database.

Assistant State Pathologist Dr Margaret Bolster visited the scene this morning as did a forensic anthropologist.

A man in his 50s was arrested on suspicion of murder on Tuesday.

He was released without charge last night and Gardaí said they were continuing investigations "into all the circumstances" surrounding Tina’s murder.

Gardaí outside the house where Tina Satchwell lived in Youghal, County Cork. Image: Jamie O’Hara/Newstalk

Tina was reported missing by her husband Richard on March 24th, 2017, when she was 45 years old.

Gardaí followed hundreds of leads and took statements from well over 100 people; however, no sign of the Fermoy native has ever been discovered.

Gardaí are continuing to urge anyone with any information on the case to contact them.

A family liaison officer has been appointed to Tina’s family.

With reporting from Newstalk’s Southern Reporter Jamie O’Hara in Youghal.