There were complaints that arrests were not made during the protests
Media photographers encouraged a group of men believed to be "hijacking" a Muslim cartoon protest in London, a Metropolitan Police briefing claims.
The briefing, obtained by the BBC under the Freedom of Information Act, gave an assessment of two demonstrations at the Danish Embassy, on 3 and 4 February.
It said the protesters on 4 February "were encouraged by a large group of photographers and cameramen".
The protests were about cartoons that had satirised the Prophet Muhammad.
Five men have been arrested over their alleged role in the first protest, on Friday 3 February.
The police briefing said there were around 450 protesters at the Danish Embassy in London that day, with about 40% of them comprising the "more vociferous element".
The document was produced on 6 February by the Met's Public Order Branch, at the request of the Home Office.
'Firm but tolerant'
Some placards and chants could be construed as "offensive and inciting violence," it said.
There were complaints by members of the public, and some politicians, that arrests were not made on the spot.
"In view of the prevailing circumstances the main thrust of the policing strategy was one of being firm but tolerant with due consideration being required before making immediate arrests," said the briefing.
It said around 3,500 people had demonstrated at the Danish Embassy in London on Saturday 4 February.
The protest was cut short by the organiser at 1240 GMT, said the police, because it was felt he wanted to "prevent the event being hijacked" by a group of around 100 young men.
The briefing said the men were "recognised as coming from East London and had masked up and refused to act on the direction of the stewards".
"Most people left the area but this group remained in a nearby street and seemed intent on some action, and were encouraged by a large group of photographers and cameramen who were following them.
"Police managed to separate the group from the media pack which resulted in the former dispersing," it added.
No news organisations or individuals were named in the document.
The briefing said that there were other similar occasions on which police had not made immediate arrests, but had done so after the event, citing May Day protests and football matches.