Two men have been arrested by the UK’s National Crime Agency (NCA) in a fraud investigation linked to the biggest property deal ever in Northern Ireland.

Searches were carried out in Co Down in connection with the inquiry into the controversial £1.2bn (€1.57bn) sale of assets and property owned by the National Assets Management Agency (Nama), to US investment firm Cerberus.

An NCA spokesman said: “Officers from the National Crime Agency have today carried out two arrests and related searches in the Co Down area in connection with a fraud investigation.

“The operation is being assisted by the PSNI.

“As the investigation is continuing we are unable to comment further.”

The investigation was sparked following the discovery of a £7m (€9.1m) offshore transfer to an Isle of Man bank account, which was controlled by a former managing partner of Belfast-based law firm Tughans.

Tughans, which was involved in the Nama transaction after being subcontracted by Cerberus’s US lawyers Brown Rudnick, insisted it was not aware of the money movement.

Nama is the so-called “bad bank” set up by the Government to take property linked-loans off the books of bailed-out banks.

A parliamentary committee at Stormont is carrying out a separate investigation into the Cerberus deal.

All parties involved in the huge £1.2 billion transaction in 2014 have denied wrongdoing.