Thirteen alleged members of Britain's biggest ever drug smuggling gang - including three from West Yorkshire - have appeared in court accused of importing cocaine, heroin and cannabis worth billions of pounds.

They were arrested in dawn raids across the country on Tuesday in an operation by the National Crime Agency (NCA).

The NCA said the gang was part of an international organised crime group and Britain's biggest drug smuggling operation ever uncovered.

Arrests were made in London, Manchester, Stockport, St Helens, Warrington, Bolton, Dewsbury, and Leeds.

The 13 have all been charged with conspiracy to import class A and class B drugs and appeared at Manchester and Salford Magistrates' Court on Thursday.

Seven defendants were remanded into custody, the NCA said.

They are Paul Green, 54, of Eccleston, St Helens; Sohail Quereshi, 59, of Wood Crescent, White City, London; Mohammed Ovais, 41, of Bournlee Avenue, Burnage, Manchester; Khaleed Vazeer, 56, of Westwood Avenue, Timperley, Manchester; Steven Martin, 48, of Chorley Old Road, Bolton; Mark Peers, 55, of Norbeck Close, Warrington and Oliver Penter, 37, of Gladstone Street, Stockport. Six others were released on bail. They are Vojtech Dano, 38, of Vulcan Gardens, Dewsbury, West Yorkshire; Ivan Turtak, 34, of Vulcan Gardens, Dewsbury, West Yorkshire; Ifthikar Hussain, 46, of Upland Grove, Leeds, West Yorkshire; Ghazanfar Mahmood, 48, of Green Lane, Bolton; Andrew Reilly, 37, of Grange Park Road, St Helens and Paul Ruane, 58, of Bewsey Rd, Warrington.

All 13 are next due to appear at Manchester Crown Court, Crown Square, on Thursday November 7.

Four men and two women from the Netherlands, who were arrested in April by the Dutch National Police on European Arrest Warrants, are currently awaiting extradition to the UK.

A further two men were arrested as part of the investigation on Thursday after handing themselves in to a police station.

The men - a 29-year-old from St Helens and a 36-year-old from Wigan - are being questioned at a Wigan police station in connection with conspiracies to import class A and B drugs.