Riot police battled throughout Wednesday to clear Britain's biggest illegal travellers' site after meeting violent resistance and a barrage of missiles on entering the camp.

Seasoned activists, who have joined the residents, hurled bricks at officers, swung spades at them and torched a caravan at the culmination of a decade-long legal battle over the Dale Farm site in southeast England.

Dozens of police carrying shields and batons forced their way into the six-acre (2.4 hectare) camp of Irish travellers, outside the town of Basildon in Essex, shortly before sunrise.

One person was shot with a Taser stun gun, while 23 people were arrested, but the camp of caravans and chalets was under control by midday, police said.

The local ambulance service said six people had been injured, with one woman taken to hospital with a minor back injury and four suffering from smoke inhalation.

Police entered the camp from the back, bypassing the 12-metre (40-foot) high scaffolding barricade erected by protesters at the main entrance.

Some female residents were in tears as the police lines approached, while travellers and activists alike shouted abuse at the officers.

People hastily erected barricades made of tyres, broken tables, wooden pallets and an old sofa, blocking off pathways in the compact site.

Resident Sherlen McCarthy, 22, was concerned as she stood watching the scenes with a friend.

"My mum has diabetes and asthma; she is in a caravan. I don't want her to see all that," she told AFP.

"When they kick us out, we'll have nowhere to go. The police will have to move us out."

Protester Janet Thomas, 57, a health service worker, said: "It's disgraceful. I can't believe this is happening in this country.

"It's absolutely horrendous. It's like ethnic cleansing. Where do these poor people go after that?"

Within hours, police had established control over the site, and then removed activists who had used bike locks to attach themselves to the top of scaffolding at the front entrance, which was preventing vehicles from entering the camp.

Heavy machinery was waiting outside the site to enter following the removal of the barricade, which police were dismantling as darkness fell.

It appeared to be the end of the high-profile campaign to block the eviction which has attracted support from Oscar-winning actress Vanessa Redgrave and a former advisor to the United Nations.

Kathleen McCarthy, a Dale Farm resident, said the eviction would "weigh heavily on Britain for generations."

Police said they had moved in following indications that violence was likely to occur, with intelligence pointing to stockpiles of missiles and liquids to be used against officers and bailiffs.

Essex Police spokesman Trevor Roe told reporters: "We are in control of the whole site. It's calm. The tension is now reduced.

He defended the use of a Taser, which fires a pair of darts into a target to stun them with a jolt of electricity, saying officers had been faced with "serious violence".

Basildon Council, the local authority, has fought a long battle with the Irish travellers, who own the land but lack planning permission to build on it.

There are tight restrictions on the use of "green belt" land, in this case the ring of protected countryside surrounding London.

The Dale Farm site comprises 51 unauthorised plots, on which caravans and some single-storey houses are home to up to 400 people, including families.

Basildon Council wanted to start the eviction last month after a court victory but the travellers have delayed the move until now using a series of legal avenues.

The local authority has set aside up to 18 million pounds ($28.4 million, 20.5 million euros) to clear the site.

Council leader Tony Ball said: "I am absolutely clear that after 10 years of negotiations to try and find a peaceful solution to this that actually what we're doing is the right thing."