Conservative mayoral candidate Boris Johnson has pledged to tackle knife crime if he wins London's May elections.

Outlining key elements of his manifesto on Monday, Johnson said he would stamp out gang culture "in a proactive way" by holding police chiefs, ministers and the mayor to account on the issue.

He pointed to Metropolitan Police commissioner Sir Ian Blair's call for a "bonfire of bureaucracy", and said he would focus on solving "the growing bureaucratic burden".

Johnson also pledged to put more police on the streets.

"We understand that there will always be a limited amount of paperwork, but we cannot see why we can't embrace new technology and learn from other police forces around the UK to get more police out on the streets so that the priority is always stamping out knife and gun crime," Johnson's manifesto said.

The Henley MP called for "an end to political correctness when tackling knife and gun crime", and announced proposals to use mobile scanners in crime hot spots around London, such as tube stations and festivals.

He called for the London Development Agency to direct funds towards the community groups which offer mentoring for young people at risk of being socially excluded, and said part of the LDA budget should be ring-fenced for sports funding.

On housing, Johnson said he would make "designing out crime" a priority when considering developments submitted to the mayor for approval.

The manifesto also included plans to improve safety on public transport safer by running a live CCTV trial on buses.

At present Johnson is neck and neck with current mayor Ken Livingstone with a recent YouGov poll showing Labour's candidate on 45 per cent and the Tory MP for Henley on 44 per cent.