Hillsborough match commander David Duckenfield gave the order to open exit gates to the ground because he thought there would be loss of life outside, a former officer has told his trial.

The former South Yorkshire Police chief superintendent, 75, was "deep in thought" before making the decision, Robert McRobbie told Preston Crown Court on Wednesday.

The jury has heard Duckenfield ordered the gates open after crowds built up outside turnstiles ahead of the FA Cup semi-final between Liverpool and Nottingham Forest on April 15 1989.

Once through the gate, Liverpool supporters were able to head down a tunnel to the already full central pens of the Leppings Lane terrace, where 96 men, women and children died in the fatal crush.

Mr McRobbie said he had been in the police control box with Duckenfield as an observer, in his civilian clothes, because he had recently been transferred to the division.

He said he remembered hearing three radio requests from Roger Marshall, the superintendent based at the Lepping Lane turnstiles, asking for gates to be opened to relieve the crush outside.

Describing the final request, he said: "It was more of a demand than a request. It was more frantic.

"It must have incorporated the words people were going to be hurt if the gates weren't opened."

He said the request was "considered very seriously" but he could not recall any advice being given by other officers in the control box, such as Superintendent Bernard Murray, the ground commander.

"Mr Duckenfield was deep in thought at that time," he said.

"But I recall Mr Murray being stood in front of him with a radio in his hand asking for a decision so he could relay it to Mr Marshall."

He told the court that Duckenfield had considered the situation before giving his decision.

He said: "Basically, it was if there was going to be loss of life or people injured outside he had no option but to give the authority to open the gates."

Mr McRobbie said he watched people coming through the exit gate on the CCTV monitors in the control box.

He said the central pens of the terrace were "very full" but there was space on the edges of the terrace.

Duckenfield, who sat in the well of the court, denies the manslaughter by gross negligence of 95 Liverpool supporters who died in the crush.

Five of those who lost their lives in the disaster were from Halton.

Under the law at the time there can be no prosecution for the death of the 96th victim, Anthony Bland, as he died more than a year and a day after his injuries were caused.

A previous trial took place in January but the jury was unable to return any verdict and was discharged.