A South Yorkshire police officer who was on duty when 96 people were killed at Hillsborough in 1989 has said that his statement about the disaster was changed without his knowledge or consent, and was manipulated before it was submitted to the original Taylor inquiry.

Sgt Stephen Thomas, who was on horseback outside the Leppings Lane end of Sheffield Wednesday's football ground when, he said, police lost control of the crowd, said there had been no discussion with him about three paragraphs of his statement being deleted.

In his original statement, which he wrote by hand two weeks after the disaster of 15 April 1989, Thomas had written three paragraphs under the heading "Police deployment". All of that section was then deleted without his consent, he said, in the version of the statement sent to the Taylor inquiry.

The section included his opinion that police numbers were too few to maintain control of the crowd: "Once the crush started [outside the Leppings Lane entrances], the numbers of officers on foot seemed to reduce dramatically."

The section also included a paragraph in which Thomas had criticised Liverpool supporters, saying that they showed too little "consideration" when the crush started and that he believed "a high proportion" had been drinking and that "a large number without tickets were just trying their luck at the turnstiles".

Other observations critical of supporters, that they had been drinking, pushing and disregarding other people's safety were retained elsewhere in his statement.

Later, questioned by Peter Wilcock QC, representing 75 of the bereaved families, Thomas accepted that he only saw one supporter without a ticket, and that his comment that he could smell alcohol in the crowd was "unreliable".

Asked about the process by which he gave his statement after the disaster, Thomas said the order came "from the top" and was communicated by his inspector, that officers should not record the events in their official police notebook.

He said notes were always made in notebooks, that they could not later be changed without it being "obvious", and that the policeman's notebook became the prime "memory prompter" if an officer later gave evidence about an event in court. He clarified that a notebook was used to record "relatively concise factual information" such as details of times and incidents, not a full account.

Thomas agreed with Pete Weatherby QC, representing 21 families, that being told not to write in his notebook was "a highly unusual request".

He explained: "At the time, the force was run in such a way, you did as you were told."

"It was your evidence being manipulated before it went off to the Taylor inquiry, wasn't it?" Weatherby asked.

"Yes, obviously," Thomas replied.

Thomas told the jury of seven women and four men that by 2:15pm-2:30pm on the day of the disaster, the police had lost control of the crowd of Liverpool supporters who had arrived for the FA Cup semi-final against Nottingham Forest. He said that supporters were pushing to try to get to the turnstiles, and he could "smell alcohol" among them.

Wilcock pointed out that in his original statement in 1989, Thomas had never said that he could smell alcohol. Thomas said in response: "I can't possibly remember whether I did or not, to be honest."

Asked if the evidence that he could smell alcohol was "unreliable", and he "should not have said it", Thomas replied: "Yes."

Of his evidence that a large number of supporters had had no tickets, Wilcock pointed out that in his statement, there was only one specific example of a supporter without a ticket – "a single youth" who had a £10 note in his hand.

"So again," Wilkcock asked him, "can we ignore your views on how many ticketless fans there were?" "Yes," Thomas replied.

Questioned by Christopher Daw QC, representing former South Yorkshire police chief superintendents Terry Wain and Donald Denton, regarding the assertion that his evidence was manipulated, Thomas said: "I felt it strange that they should take out the criticism regarding the police deployment, yes."

He agreed, however, that the criticism of the fans which was also taken out would have been helpful to anybody seeking to blame the supporters for the disaster.

A second witness, Inspector Keith Wilkinson, one of 14 mounted officers from Merseyside police who assisted at Hillsborough, denied that he was told or encouraged "by others" to change his first statement about the disaster to emphasise bad behaviour by Liverpool supporters. The inquest heard that Wilkinson made his first statement on 24 April 1989, then a second in January 1990.

In his first statement, Wilkinson had noted that at one point outside the ground, before the lethal crush happened, some supporters had been standing around on a bridge, blocking the pavements, so officers asked them to move along. Wilkinson had written: "There was no hostility, and most moved when requested."

In his second statement, Wilkinson added of the supporters on the bridge: "Some of these people were drinking alcohol from cans and bottles."

Wilkinson also added in his second statement that these supporters were making it "difficult" for other pedestrians to cross the bridge. He also removed the sentence that the supporters had moved along "without hostility."

In addition, Wilkinson added in his second statement that he believed in the crush of supporters outside, his horse had been hit on the head. He had not mentioned that in his first statement, made nine days after the disaster, and he told the inquest he did not know if his horse had in fact been hit on the head and had not seen it happen.

Wilcock asked why, after 95 people had been killed at Hillsborough, when Wilkinson made a second statement nine months later, the only elements he sought to change were the additions of supporters drinking, that they had been causing a difficulty for others, his belief that his horse may have been hit on the head, and his removal of the observation that the supporters had moved along "without hostility."

"Is it the case that you have been encouraged by others to accentuate the negative and eliminate the positive as far as the behaviour of Liverpool fans is concerned?" Wilcock asked him.

"No," Wilkinson replied, "that is not the case."

Wilcock said the court will hear that "a number" of Merseyside officers, who had been on duty at Hillsborough, made second statements on 11 January 1990. Wilkinson said he could not remember that, or remember making his second statement, and did not know why he had made the changes.

"Are you trying to hide something?" Wilcock asked him.

"There is nothing to hide," the officer answered.

The inquest, in Warrington, continues.