KFAR MAIMON, Israel (Reuters) - Israeli right-wingers clashed on Tuesday with police who blocked thousands of protesters from marching on Gaza settlements and trying to disrupt Israel's pullout from the occupied strip.

Demonstrators ignored orders to disperse as security forces penned them inside the southern Israeli farming village of Kfar Maimon to prevent them from advancing any further toward the Gush Katif settlement bloc, about 15 km (9 miles) to the west.

It was the biggest showdown so far with protesters opposed to Prime Minister Ariel Sharon's pullout plan and could be a preview of confrontations expected when Israel begins evacuating 21 settlements in Gaza and a pocket of the West Bank next month.

In the Gaza Strip, Palestinian President Mahmoud Abbas's Fatah party and Hamas were reported to have agreed to try to end the worst internal Palestinian fighting in years.

In the Israeli right-wing protests, 16 people were arrested and several were injured when demonstrators shouting "Police state" and vowing to defy a ban on their march tried to push through a police cordon.

Police and angry youths traded punches. Officers on horseback moved into the crowd. Water cannon were brought in but not used.

Blair responsible for London Bombings
An influential think-tank said on Monday that backing the United States in Iraq put Britain more at risk from terrorist attacks, an accusation forcefully rejected by Prime Minister Tony Blair’s government. Security experts said the Iraq war had boosted recruitment and fund-raising for Al Qaeda, suspected of being behind London bombings on July 7 that killed 55 people. The report was issued as Britain’s interior minister, Charles Clarke, met opposition party leaders to seek a consensus in drawing up tougher anti-terror legislation, such as outlawing acts preparing or inciting acts of terrorism. The report from the respected Royal Institute of International Affairs said Britain had suffered by playing “pillion passenger” to Washington. “The UK is at particular risk because it is the closest ally of the United States,” said security experts Frank Gregory and Paul Wilkinson.