The mother of missing student Megan Roberts has said the disappearance of her "beautiful daughter" appears to be the result of "a tragic run of events with no one to blame".

York St John University student Miss Roberts, 20, has not been seen for more than a week since she disappeared during a night out with friends in the city.

North Yorkshire Police have said they believe the most likely explanation for her disappearance is that she got separated from her group while under the influence of alcohol and fell in the River Ouse near to York's Lendal Bridge.

Her mother Jackie Roberts has posted a message on a special Facebook page dedicated to finding Megan.

Mrs Roberts said: " Thank you for all your support and kind thoughts.

"The police have been amazing, they are doing all they can to find her. We've been given as much information as the police can give us and all evidence does point towards this being a tragic run of events with no one to blame.

"Until we know for certain, we all have hope, but whatever the outcome, we are all carrying Megan in our hearts.

"This is a very difficult time and, as a family we will always be thankful for everyone's love and support and caring thoughts for my beautiful daughter."

Divers from the regional police underwater search unit spent the weekend searching the River Ouse for Miss Roberts, who is from Wetherby, West Yorkshire.

A spokesman said the team was using sonar equipment to scan the water from Lendal Bridge downstream to Naburn.

Miss Roberts was last seen on CCTV on the corner of Rougier Street and Lendal Bridge at around 2.20am on January 23. She was reported missing a week ago today.

A week after her disappearance, Superintendent Phil Cain said: "The strongest and most probable line of inquiry being pursued by police is that Megan, affected by alcohol, has entered the river."

Mr Cain stressed that there was "no evidence to indicate foul play".

Miss Roberts was with a group of friends who had been drinking "for several hours" before leaving the Popworld nightclub, in York city centre, at around 2.10am on Thursday morning.

Police said the group were spread out and some of them ran down a street called Tanner's Moat, past The Maltings pub, where Miss Roberts - the last in the group - was spotted bumping into a row of cycle racks.

There is no CCTV footage of her returning up the hill.

Miss Roberts is described as around 5ft 6in and of medium build with long dark brown hair. When last seen, she was wearing a cream knee-length dress which had large brown and orange flowers on it and black plimsoll-type shoes.

Miss Roberts is studying fine art at the university and lived in the Clifton area of the city.

It is thought her friends believed she had gone to stay with her family, just 10 miles away in Wetherby, where she lived with her mother and two younger siblings, understood to be brother Ben, 14, and Amy, 16.