Sniffer dogs have found millions of pounds worth of heroin woven into hand-made rugs.
The seizure was made at Manchester Airport when Border Force officers became suspicious of a 46-piece consignment of hand-made knotted carpets or rugs that had arrived from Peshawar in Pakistan via Abu Dhabi in the Middle East.
A sniffer dog alerted its handler to one of the carpets and further examination revealed a highly sophisticated concealment where the drug was woven into the fabric of the carpet.
Several other carpets also tested positive for heroin.
Around 50 kilos of heroin have so far been found since the drugs were found on April 24, but examination of the load is continuing and the final total could be far greater.
The haul is already among the largest drug seizures made at Manchester Airport and it is thought the total value of the drugs could run into millions of pounds, the Border Force said.
Following an investigation by officers from the National Crime Agency's (NCA) Border Policing Command, two people were arrested on suspicion of drug importation offences at a business address in London on April 29.
They are on bail pending further inquiries.
Linda Paul, assistant director for Border Force, said: "This is an extremely impressive seizure and I would like to praise the vigilance and hard work of my officers who have ensured that a substantial amount of a harmful drugs have been kept off our streets.
"At this stage it is impossible to put an exact value on the drugs because forensic tests have yet to be carried out. However, it is safe to say that we are looking at a significant amount."
Pete Avery, from the NCA's Border Policing Command, said: "This was a first class detection by Border Force officers of a huge quantity of heroin worth millions.
"It was a sophisticated concealment and demonstrates the lengths organised crime groups go to in an effort to avoid detection. Our investigation has resulted in two arrests so far and inquiries are ongoing."
Anyone with information about activity they suspect may be linked to smuggling should call our hotline on 0800 59 5000.