About 300 people are thought to be begging in Westminster

Beggars are being reported, arrested and having DNA and fingerprints taken.

Westminster Council says the move is an audit of the problem's scale but shelter charity Crisis says the move will "criminalise" the homeless.

Fifteen people were arrested on Friday night and two more on Saturday, a Metropolitan Police spokeswoman said.

Of these, 14 were arrested for begging, while three others were charged with "offences relating to the operation", including drunkenness, public disorder and theft.

It is thought there are 10 times as many beggars in Westminster as in Manchester, many of them coming from outside London to target tourists.

Persistent beggars or those found near cash machines may be issued with anti-social behaviour orders if they are convicted.

We are talking here about some of the most vulnerable people in society Shaks Ghosh, Crisis

But Shaks Ghosh, chief executive of Crisis, told BBC Radio 4 the scheme would not work.

"It's expensive and it displaces the problem out of Westminster to other London boroughs.

"We want to see long-term solutions, not just people being churned through the criminal justice system.

"We are talking here about some of the most vulnerable people in society."

'It is not a stunt'

But Westminster Council described it as a "comprehensive effort" to harass and deter aggressive beggars.

It said it was a response to surveys of visitors and residents who had complained of feeling threatened, and said social workers would be on hand help those arrested.

Westminster Council's leader Simon Milton said: "It's not a stunt. It's essential to track the activities of beggars if we are to take effective measures [against them].

"The trouble we have had in the past with simply arresting people is that, because they weren't being fingerprinted, they were simply released again and there was no disincentive to continue begging."

An estimated 300 beggars operating in just a few square miles around areas including Soho, Covent Garden and Piccadilly, will be targeted.