One driver has alleged he was pulled from his pedicab and assaulted in the city centre by a group of off duty-taxi drivers, while another said he was threatened with an attack with a Taser stun gun by a disgruntled cabbie.

The pedicab drivers, who are mainly students, say taxi drivers have also thrown cigarette butts at them.

The attacks are being blamed on a core minority of cabbies who see the bicycle rickshaws as muscling in on their livelihood. But taxi chiefs said they had not received any complaints, adding there was growing tension between the two camps because of the increase in the number of pedicabs on the city's streets in recent years.

Neil Hartop, 28, a rickshaw driver from Marchmont, claimed he was attacked in the early hours of November 25th on George Street by three men who told him they were all black cab drivers.

He said: "They got in and started kicking my back, saying they were fed up with the pedicabs. I stopped and said I wasn't taking them any further and one of them headbutted me.

"I fell to the ground and they kicked me before they got in the back of a taxi. I was really shook up but thought I would just get more hassle if I reported it."

Police chiefs today said they had no recent reports of attacks, but urged victims to come forward. Phil Varley, the owner of Edinburgh Pedicabs, said: "It is obviously concerning for our drivers, but it only seems to involve a hardcore minority of taxi drivers."

A fleet of around 60 pedicabs is estimated to operate at weekends, compared with just two in 2000.

Murray Fleming, secretary of Central Radio Cabs, said: "It is very easy to cast aspersions. More generally, there is concern among the taxi trade about the safety aspects of pedicabs and the big increase in their number."