Haitian President Jean-Bertrand Aristide faced increased pressure to resign Monday after four days of rioting led by armed rebels killed as many as 40 people and led to widespread looting.

Prime Minister Yvon Neptune accused the opposition of trying to mount a coup to overthrow Aristide, who won legislative elections in 2000, but international observers called the vote seriously flawed.

Three major centres, Gonaives, St-Marc and Grand Goave, were under control of the rebels on Monday, as well as several smaller towns.

In a number of places, rebels or opposition groups set fire to police stations and blocked roads.

The capital, Port-au-Prince, remains under government control.

At least 69 people have died in Haiti since September, when anti-Aristide sentiment turned into violent clashes. The latest round of violence has killed an unknown number of people, with estimates ranging from 18 to 40.

Haiti's population of eight million occupies one-third of the 650-kilometre-long Caribbean island of Hispaniola, with the Dominican Republic taking up the other two-thirds.