A mother has said she fears the disappearance of her son will "become a cold case".

Ali Durrani, from Stirchley in Birmingham, has not been seen by his family for 120 days. He went missing one evening in February, and was last seen talking to a woman at a bus stop.

Relatives believe it is extremely out of character for the 32-year-old, who vanished "completely out of the blue" after telling his family he was going for a walk.

West Midlands Police said the search for Mr Durrani remained active and they were continuing to pursue active lines of enquiry.

"Our life has been turned completely upside down," his mother Mahjabeen said.

"We are completely devastated and can't function properly."

Ms Durrani added her son, who studied economics at the University of York, had told her he was going out for a walk to clear his head.

The family were close and would often eat their evening meal together.

But Mr Durrani did not return and was last seen talking to a woman at a bus stop in Turves Green, Northfield, at about 17:25 GMT on 6 February.

"There's nothing to say he wasn't going to come back," Ms Durrani continued.

"There is no note, nothing at all."

Mr Durrani had anxiety and relatives said he had been trying to find a job, but he had no history of significant mental health issues.

The family have launched a social media campaign asking for information, but his mother said it felt like they were going "round in circles".

She said she was worried about how long it was taking police to obtain CCTV, and worried her son would be forgotten about.

"I don't want this to become a cold case," she said. "We will carry on looking for our son that's the most important thing to us.

"I believe he's out there somewhere I absolutely believe that."

The missing man, who enjoyed walking and the outdoors, is described as medium build, with black hair and a black beard.

He was last seen wearing a green raincoat with black jeans and lace up brown shoes.

Neither his bank or social media accounts have been used and his passport was left at home.

West Midlands Police said it understood the concerns of Mr Durrani's family and was still investigating.

"We will be speaking with them to understand their concerns and will seek to reassure them of the extent of our enquiries," a statement said.

The Missing people charity said the reasons why people go missing were complex and varied.