The vessel has been taken into Harwich docks led by HMS Vigilant.
"A vessel which had been heading to Libya returned to the UK Wednesday morning," The Mirror quoted a Home Office spokesman as saying Friday.
"The ship was escorted into the port of Harwich by the UK Border Agency cutter HMS Vigilant.
"A number of containers were offloaded from the boat and have been taken under control of UK Border Agency and have been moved to a secure location," he said.
"The cargo is understood to contain a significant quantity of Libyan currency, which is subject to a UN sanction."
Some reports suggested the vessel was carrying 100 million pounds worth of the Libyan currency, the dinar.
The Home Office, however, have refused to confirm the exact value of the seized money.
It is understood the ship was intercepted after being tracked to British waters when it aborted an attempt to dock in the Libyan capital Tripoli over the weekend.
Britain has already prohibited unlicensed export of any uncirculated Libyan banknotes from the country in line with UN sanctions.