The father of Claudia Lawrence, the university chef who went missing in York in 2009, expresses concern

Police hunting for a missing university student are focusing their search on the river which runs through the city where she disappeared.

Specialist police teams were searching a river in York last night for a student who went missing on a night out with friends, without anybody raising the alarm for more than four days.

Police said there was no suggestion of criminality over the disappearance of Megan Roberts, who was last seen in the early hours of Thursday.

CCTV footage showed her walking with a group of friends on one side of the River Ouse on their way home. Other cameras picked up the group on the other side of the river having apparently crossed Lendal Bridge in the centre of the city, but there was no sign of the 20-year-old.

Ms Roberts was reported missing by her mother on Monday morning after a friend raised the alarm. An underwater search team was searching in the river while other officers scoured the banks for any sign of the student from York St John University.

Police have investigated a message on her Twitter feed posted six days before her disappearance in which she complained about a man who followed her from a pub to a second one. “Can’t believe a guy just followed us from one pub to another and came in and sat down next to us, staring at us like it was completely fine,” she wrote.

A police diver enters the River Ouse near Lendal Bridge in York in the search for missing student Megan Robert (PA)

Superintendent Phil Cain said: “We are exploring with friends who are aware of a Twitter message, which was commenting about a male in a bar where Megan was at the time.

“Friends are convinced there was nothing to suggest Megan was being stalked at that stage. We do not believe that is connected to Megan’s disappearance. At this moment in time there’s no suggestion of any criminality whatsoever and we are treating this as a missing from home.”

Ms Roberts was last seen at around 2am on Thursday in the Popworld nightclub on George Hudson Street. The student, who is around 5ft 6in tall and of medium build with long dark brown hair, was wearing a cream knee-length dress patterned with large brown and orange flowers and black plimsoll-type shoes.

A spokesman for Peter Lawrence, the father of Claudia Lawrence, the university chef who went missing in York in 2009 and has never been found, said that his prayers were with the missing student’s family and friends.

“The 100-plus hours between when she was last seen early last Thursday morning and the reporting today makes it very difficult for those looking for her, whether police, family or friends, as the first few hours of being missing are critical,” he said.

Ben Bason, from University Radio York, said the broadcaster was doing its bit to help in the search. “We’re trying to trigger anyone’s memory who might have been out on Wednesday night and might have seen her,” he said.