Iraqi insurgents have intensified their attacks on American targets inside the restive city of Falluja and outlying villages and towns.

U.S. troops have been taken aback by these daring attacks, in a city where the majority of its nearly 300,000 residents are unhappy with the presence of the American invaders.

Not only in Iraq but across most of the Arab and Muslim world, Falluja has become a symbol of the anti-U.S. resistance.

In 2004, it took the mighty American military over a month to flush out the rebels. The battle to regain the city caused massive destruction, turning most of it into a heap of ruins.

But the rebels, most of whom had retreated to the countryside to escape the devastating firepower of the United States, have reorganized themselves and are now using more sophisticated means to drive out the Americans.

Two trucks - one loaded with explosives and the other with toxic gas - penetrated the fortified U.S. military camp in the city. The first suicide bomber drove through the gate with his explosive-laden truck, only to be followed by the second truck full of chlorine bombs.

The rebels interpret the massive American attack on Falluja in 2004 as a defeat for the United States and a turning point in the battle to force its troops out of the country.

In the attack on the U.S. base, the second truck filled with chlorine gas actually entered the camp. The Americans have yet to release any reports on casualties, but Iraqi police sources say tens of people, mostly Iraqi police and U.S. servicemen, were killed or injured.

The United States has placed the city under a strict curfew, which is in its third day and bans people and trucks from exiting or entering the city, further fuelling popular resentment and anger at their tactics.

Despite the presence of thousands of U.S. troops inside and outside the city, the rebels still seem to have the upper hand. They are in almost complete control at night and carry out hit and run attacks during the day.