Media playback is unsupported on your device Media caption Brian May: "We don't believe it will work, we don't believe it's humane"

Several hundred people have held a rally in London as licences to cull badgers came into force in two areas.

Up to 5,094 free-running badgers in west Somerset and west Gloucestershire can now be shot by trained marksmen.

Ex-Queen guitarist Brian May, who led the rally, said the cull would not make "life any easier for farmers", adding: "We don't believe it will work."

Farmers believe badgers spread TB and have led to rising numbers of infected cattle being slaughtered every year.

'Smash the BNP'

Groups of farmers in the two pilot zones have been given licences to conduct culls using trained marksmen to shoot the distinctive black and white creatures.

The cull can take place over any continuous six-week period until 1 December.

Campaigner Paul Hornsby said: "Yes I live in a city, but I have a family of foxes living in my back garden and I believe it's their world too.

Image caption Hundreds of people - and some with their pets - took part in the anti-badger cull rally earlier

"I don't believe we have any right to kill these animals, badgers or foxes."

A minor scuffle broke out as the rally was not allowed to proceed to Parliament Square or Westminster Abbey because a BNP march was taking place.

A group of anti-cull protesters set fire to a pile of newspapers, causing smoke to drift over the grounds of the Houses of Parliament.

Eyewitness Ryan Barnes said anti-BNP and anti-cull protesters later began chanting "Save the badgers, smash the BNP" together.

'Terrible price'

During the rally, which was attended by an estimated 1,500 to 2,000 people, May also renewed calls for ministers to change their mind about the cull.

He said: "The great bit of new information is it has now been demonstrated that the cull cannot make economic sense.

Media playback is unsupported on your device Media caption Up to 5,094 badgers can be culled in the two pilot cull zones in west Somerset and west Gloucestershire

"It will lose the taxpayer money rather than save it.

"That was really the last shred of reason that you could give for this cull going ahead.

"It is a very good time for Mr Cameron to reconsider and withdraw from this monstrous cull, in the public interest."

He also delivered a near-250,000 signature petition to Downing Street calling for the cull to be scrapped.

The government argues that the cull is necessary as part of efforts to stop spiralling numbers of outbreaks of TB in dairy and beef herds, which led to 28,000 cattle being slaughtered in England last year.

Without action, infection and costs will continue to soar, it is claimed.

What we're trying to see in these pilot culls is whether it can be done humanely, safely and efficiently Farming minister David Heath

Labour, which is against the cull, has tabled an opposition debate in the Commons for Wednesday.

'Humane culls'

A YouGov poll released on Friday showed 34% of people oppose a cull, 29% support the measure, while the remainder did not know or had no strong feelings.

A long-term study has shown that culling 70% of badgers in a particular area can reduce the disease in herds by 16%.

In west Gloucestershire the aim is to shoot up to 2,932 badgers in the first year of the cull.

In west Somerset, the target is 2,162 badgers, bringing the total number to 5,094 in this period.

This will equate to about 70 badgers being killed every night in west Gloucestershire and about 50 a night in west Somerset.

A third area, Dorset, is being considered for a cull, but a licence is not yet in place.

Farming minister David Heath said: "What we're trying to see in these pilot culls is whether it can be done humanely, safely and efficiently."

He said the culls were part of a wider strategy to improve bio-security, and that vaccines - suggested by opponents of the cull - were not ready yet and could not be used effectively.

He said other countries such as Ireland and New Zealand had adopted "similar policies" successfully to deal with the issue.