A man suspected of being the head of an organised crime gang has been arrested in Lithuania, the UK National Crime Agency (NCA) said.
James Mulvey, 40, faces an extradition hearing in the capital Vilnius on Thursday after being held in a raid by armed local police in the country's second city, Kaunas.
Mulvey, who is originally from Solihull in the West Midlands in England, was subject to a European arrest warrant over a drug haul including 365kg of cannabis and 20kg of cocaine destined for Ireland that was found in Belgium in 2007, the NCA said.
A gun, 100 rounds of ammunition and two ballistics vests were among items seized at two buildings in Lithuania raided, a spokesman added.
The NCA's operations manager Adam Warnock said: "The NCA's international partnerships mean we can extend the UK's reach overseas to combat criminal networks and the serious financial crime which props them up.
"James Mulvey has been targeted by the NCA, the West Midlands RART and HMRC as we believe he heads a crime group involved in drug trafficking, money laundering and a multi-million pound VAT fraud.
"Our investigation is ongoing."
Five other people were arrested in the Midlands and Somerset on Tuesday on suspicion of being part of a gang involved in a multi-million pound VAT fraud and money laundering.
The five, a 42-year-old woman from Charlton Adam, near Glastonbury in Somerset; a man aged 37 from Tamworth in Staffordshire, a 50-year-old man and a 25-year-old woman from Wythall in Worcestershire and a 58-year-old man from Atherstone in Warwickshire, were later released on bail.
Around £40,000 in cash and computers were also recovered following an investigation by the NCA, the pan-police force West Midlands Regional Asset Recovery Team and HM Revenue and Customs.
Police on Mauritius also raided addresses in Tamarin area of the Indian Ocean island and confiscated digital equipment and documents, the NCA said.