Detective Constable Tim Friend, the investigating officer, said that the robberies had all taken place around the same location, where vulnerable women had purposely been targeted:

“The first incident took place on Friday, 28 May around 12.20pm in the alleyway that runs between the Handsworth Booth tram stop and Earlsmead Road.

“The victim, a 78-year-old woman from Birmingham, was walking through the alley when a man approached from behind and walked past her, before turning and pointing a knife towards her.

“He calmly demanded she give him all of her money at which point she handed him all she had, being £6 in change.”

The second incident occurred nearly two weeks later on Thursday, 6 June 2010, at the Handsworth Booth Street tram stop.

DC Friend continued: “Around 2pm the victim, this time a 30-year-woman from Birmingham, was waiting at the tram stop on the Birmingham bound platform.

“She was waiting with her two children and another child, talking on her mobile phone, when the man approached and asked about the tram times.

“Suddenly the man grabbed her phone, ripping her earring from her ear, and made off along the platform.”

As the victim and her eldest son gave chase, the man turned and pointed a knife at them, before making off away from the tram stop.

DC Friend added: “The third robbery took place on Friday, 11 June 2010 on the footpath between the tram stop and Booth Street.

“On this occurrence, around 9pm, the man targeted a pregnant 30-year-old woman as she walked away from the tram stop, toward Booth Street.

“The man threatened her with a knife and demanded that she hand over her money and phone.”

Fearing for her safety, and that of her unborn child, the woman handed over £21 in cash as well as her mobile phone, before the man made off.

DC Friend said: “These incidents left each victim shocked and intimidated, and we are determined to catch the man responsible.

“The man targeted these individuals because of their vulnerability, making these attacks even more callous.

“We are making local enquiries, including working closely with colleagues from West Midlands Police, and ask that anyone who witnessed any of these robberies, or who recognises the man, come forward.”

The man is described being Asian, around 5’6” tall, with a medium build. He had short, course, dark hair and dark eyes. He was clean shaven and softly spoken.

The knife he was carrying, on two occasions, is described as being around 25-30cm in length, with a smooth blade and a yellow handle.

Anyone with information is asked to contact British Transport Police on 0800 40 50 40 quoting reference B10/WWA of 22/07/2010.

Alternatively they can contact West Midlands Police and ask for CID at Handsworth on 0845 113 5000 or Crimestoppers on 0800 555 111.

If you see this man, do not approach him, but call police immediately on 999.