Lifeboats have been launched from the Kent coast and are heading towards a cargo ship taken over by migrants thought to be wielding metal bars.

RNLI stations in Margate and Ramsgate have both launched vessels heading towards the container the Grande Tema.

It is understood four stowaways are trying to take control of a ship and get its crew to veer it closer to shore.

The crew members have locked themselves into a room for safety.

Paul Kyprianou from the Grimaldi Lines, which owns the vessel, said: "They are armed with iron bars and they have been threatening the crews this morning requesting they must get close to the shore.

"The crew members are locked on the bridge and are in direct contact with the UK authorities."

The migrants are thought to have been discovered on the ship four days ago.

Mr Kyprianou added: "They were put in a cabin, and given accommodation, food and anything needed.

"Obviously they had to be guarded in order to avoid any reaction from their side, which unfortunately took place this morning."

An Essex Police spokesman said: "We continue to deal with a complex incident on board a vessel that is in the Thames Estuary close to the Essex and Kent borders.

"This follows a call relating to the safety of crew on board at around 9.15am today.

"We have received no reports that anyone has been harmed and don’t believe they are at risk.

"We are not currently treating this as either a hostage, piracy or terror-related incident.

"We are working closely with our partners to resolve this incident as quick as possible.

"We are not in a position to provide any details about who is on board at this stage."