The police chief at the 1989 Hillsborough stadium disaster admitted on Tuesday that his failure to close a tunnel was the "direct cause" of the deaths of 96 Liverpool supporters.

David Duckenfield had earlier told an inquest that it was his decision to open an exit gate that allowed fans to stream into two already packed pens at Sheffield Wednesday's Hillsborough ground, causing a fatal crush.

Asked by a lawyer representing Britain's Police Federation if the failure to close the tunnel leading to the pens had been the direct cause of the tragedy, Duckenfield replied: "Yes sir."

The tragedy, which occurred at the beginning of an FA Cup semi-final between Liverpool and Nottingham Forest in April 1989, was the worst sporting disaster in British history.

Duckenfield, 70 and now retired, was responding to questions from Paul Greaney QC during his sixth day of evidence at a purpose-built court in Warrington, northwest England.

Asked if it was true that he "froze" prior to giving the order to open the gate at the stadium's Leppings Lane End, Duckenfield replied: "Yes sir."

Pursuing his questioning, Greaney asked Duckenfield if closing the tunnel leading to the two pens would have "prevented the tragedy", to which the former police chief again replied: "Yes sir."

Duckenfield admitted failing to recognise that there was a need to close the tunnel.

Greaney then stated: "That failure was the direct cause of the deaths of 96 persons in the Hillsborough tragedy."

Duckenfield responded: "Yes sir."

Greaney also asked Duckenfield if he had been incompetent in his role on the day of the disaster.

Duckenfield answered: "I think it is a view some would agree with, sir."

The probe, which is made up of multiple inquests into the individual deaths, began in March 2014 and is expected to last until at least November.

The original coroner's verdicts were quashed in 2012 amid claims of a police cover-up, following a campaign by victims' families.