Officials from St Paul's Cathedral and the wider City district are considering legal action to force protesters to remove a camp set up outside the church more than a week ago, following an impasse between the two sides.

The cathedral has been shut since Friday afternoon after its dean, the Right Reverend Graeme Knowles, said the presence of more than 200 tents and marquees beside the building's western edge was an unacceptable fire, and health and safety risk. Both he and the cathedral's canon chancellor, Giles Fraser, have publicly urged the activists to leave. It is the first time the cathedral has been closed since the second world war, and church officials say it is costing St Paul's around £20,000 a day in lost visitor revenues.

The Occupy the London Stock Exchange movement, part of a wave of similar global protests against the perceived excesses of the financial and banking systems, says it is sympathetic to the cathedral's plight but believes the closure is an overreaction. Members of the group say they have received assurances from the fire service and Health and Safety Executive that the camp poses no such risk.

With the deadlock seemingly set to continue, St Paul's and other nearby institutions have consulted lawyers about possible efforts to forcibly evict the protesters. Cathedral staff were due to hold an emergency meeting with fire officers, police and officials from the Corporation of London, which administers the City district, on Monday. A St Paul's spokesman, the Reverand Rob Marshall, said the impact of the closure would be felt more intensively next week as tourist numbers swell during half-term.

"The penny is dropping," he said. "Half-term has started and we've got hundreds and thousands of visitors from around the world in London. It will soon begin to dawn that the cathedral will not be open for the foreseeable future. It's such a chunk of a visitor's itinerary and there will be a momentum that this is a reality. If there is no sign of movement in the early part of the week there will be further negotiations."

The Corporation of London has not commented publicly since Friday, when it also called on the camp to disband. But the organisation is known to have consulted lawyers about how an eviction might take place, and whether the legal options could even include an emergency injunction to clear the space immediately.

But this is seen as a last resort. Aside from the potential public relations disaster of police officers dragging peaceful protesters from their tents in the shadow of a cathedral, eviction proceedings would most likely take some weeks.

Part of the land housing the camp is owned by St Paul's, who would need to take action for trespass, while other parts belong to the Corporation, requiring a case under laws relating to obstruction of the highways. The Occupy movement has said it, too, has been taking legal advice, and cannot be expected to leave voluntarily without more information from St Paul's.

Ronan McNern from the group said: "If this is so serious, that St Paul's has been closed, shouldn't they be telling us? Aren't they putting us at risk? We want dialogue, we want proper open dialogue rather than statements through the media by the dean."

Yesterday Todaytourists and regular worshippers expecting to join the usual half-dozen services over the day were being directed to nearby churches.

Inside the cathedral there was only a private holy communion for clergy, organised to comply with an Anglican statute requiring all cathedrals to hold such a service every week. Some would-be visitors were caught out. "We didn't know, so we're very disappointed," said a woman from a visiting American family forced to suddenly revise their plans for the day. But others remained positive. "I suppose you could say we're part of the 99% as well," said Levin Brunner, an IT consultant from Munich, using the term coined by activists for the bulk of people who do not enjoy stellar salaries and annual bonuses. "We have similar protests in Germany, so we knew this was taking place and we have a lot of sympathy for it. It's very interesting for tourists to see, anyway."

Complicating matters still further is an offshoot of the St Paul's camp, set up on Saturday at Finsbury Square, a small grassed area slightly further to the east, on the fringes of the financial district, which now has around 40 tents.

Activists insist this is not intended as a replacement for the main protest, but primarily a spillover as the original site is too small to accept more tents.

Fabian Flues, a 26-year-old consultant, said he had moved to the new site after four nights at St Paul's: "This new site is actually even closer to my office. I can spend the night here and have a shower and get changed when I get to work."