Four alleged stowaways accused of threatening to kill sailors and attempting to hijack a cargo ship have appeared in court.

Special forces swooped on the Grande Tema ship in the Thames Estuary as the alleged incident unfolded in December.

Samuel Jolumi, 26, Ishola Sunday, 27, Toheeb Popoola, 26, and Joberto McGee, 20, appeared from custody at Basildon Crown Court on Friday wearing light grey sweatshirts and flanked by security guards.

All four pleaded not guilty to attempting to hijack the ship, making threats to kill and affray.

Judge John Lodge remanded them in custody to appear before the Old Bailey on April 8 for a directions hearing.

A provisional trial date of October 2 was set and listed for six weeks.

The defendants, two of whom were assisted by an interpreter, spoke only to deny the charges and confirm their particulars, with McGee giving his nationality as Liberian and the others saying they are Nigerian.

All four, of no fixed address, are said to have boarded the 71,000-tonne vessel in Lagos, Nigeria, 11 days before it neared British shores on December 21.

After becoming aware alleged intruders were roaming the ship, the 27-strong crew holed themselves up in the bridge and kept control of the vessel.

The ship's operator has said the men were detained after members of the Special Boat Service (SBS) were airlifted on to the vessel, which was carrying toxic chemicals.

Essex Police were called at about 9.15am on Friday December 21 over concerns about the safety of the crew.

GPS trackers showed the ship sailing in circles in the Thames Estuary before it docked at the Port of Tilbury in Essex at 4.20am the next day, according to MarineTraffic.com.

The ship's operator, Grimaldi Lines, said there were no reported injuries.