A five-bedroom house was one of the assets frozen

The allegations were made in papers lodged at the High Court in Belfast.

The agency said the house in Coleraine in County Londonderry, 10 acres of land and stables were owned by Patrick Fleming and others.

It said while "the majority of these assets were purchased and held in the name of Valerie Hook, the true owner is her son-in-law Patrick Fleming".

It alleged the assets "had been bought and improved with the proceeds of Mr Fleming's illegal drug dealing".

An equestrian exercise arena, Nissan jeep, 15 horses and a horsebox were also seized.

The frozen assets are estimated at about �460,000, said the agency.

Last week, it carried out searches of two premises - a five bedroom detached property and an apartment in the Coleraine area.

Search and seizure warrants were granted by the High Court.

A quantity of evidence and �36,000 in cash were seized, said the agency.

Following the searches, an interim receiver appointed to act on behalf of the High Court took control of the assets.