By Joe Penney and Mathieu Bonkoungou
OUAGADOUGOU (Reuters) - Police fired teargas at rock-throwing protesters after tens of thousands marched through Burkina Faso's capital on Tuesday calling for President Blaise Compaore to scrap plans to change term limits to stay in power.
An early morning march through the heart of Ouagadougou was peaceful but clashes erupted later as protesters tried to advance towards the National Assembly.
Tuesday marked the start of a civil disobedience campaign by opposition parties after the government asked the National Assembly to order a referendum on changing the constitution to let Compaore seek re-election next year rather than step down.
Former colonial power France, which uses Burkina Faso as a base for Special Forces soldiers operating across West Africa, urged Compaore to abide by an African Union charter stipulating that leaders should not change the law to try to stay in power.
"The people have decided to start a general popular resistance. The first grievance is to get the withdrawal, pure and simple, of this legal project," Zephirin Diabre, head of the opposition delegation, told the crowd of demonstrators.
Protesters chanted "Step aside!" and "Don't touch Article 37", referring to the clause in the constitution that now bars Compaore, in power for 27 years, from running again next year.
Others carried banners comparing Compaore to Ebola, the virus that has killed nearly 5,000 people in the nearby states of Liberia, Guinea and Sierra Leone.
"We must disinfect ourselves," one read.
There was no immediate figure for arrests or casualties, though Red Cross workers and emergency personnel took charge of some protesters injured during the demonstration.
In a statement issued late on Tuesday, the government congratulated the opposition leadership for what it said were largely peaceful demonstrations across the country. It said marchers in some towns had deviated from planned routes, however, leading to misbehavior.
"The government calls upon the sense of responsibility and restraint in order to avoid any act that might compromise the peace and stability our country holds so dear," the statement said.
Protesters in Ouagadougou who marched towards the National Assembly, where the law will be debated on Thursday, were blocked by security forces who fired volleys of teargas and used water cannons.
They responded by burning tires and throwing rocks. A pocket of demonstrators gathered in a downtown square pledging to hold out until Compaore shelved his plan, but were peacefully dispersed by police in the early evening.
"It's provocation. They (the authorities) want to set the country on fire," said a young protester. "Even if Blaise Compaore burns the country down, he will depart all the same."
Demonstrators in Bobo Dioulasso, Burkina Faso's second biggest town, 330 km (205 miles) to the southwest of the capital, pulled down a statue of Compaore, a witness said.
They left intact an adjacent statue of Libya's late leader Muammar Gaddafi, who was a popular figure in some poor African countries because of his generous cash donations.
The French government said on Tuesday it expected Compaore to adhere to laws drawn up by his peers.
"The African Union charter on democracy and good governance article 23 ... specifies clearly that constitutional revisions aiming to prevent political change are banned," Foreign ministry spokesman Romain Nadal told reporters.
Nadal said breaking the charter could lead to sanctions. President Francois Hollande had sent a letter to Compaore on Oct. 7 outlining this position, he added.
French troops based in Ouagadougou are a key part of French counter-terrorism operations across West Africa.
Compaore has positioned himself as a key mediator in regional conflicts and is also an important ally of the United States in the regional fight against al Qaeda-linked Islamists.
Having seized power in a 1987 coup, Compaore has won a series of elections, the last of which was in 2010.
But he faced unprecedented protests in 2011 from a usually loyal army. The referendum plan has split his nation, one of the world's poorest despite being a top regional cotton producer and home to a fledgling gold industry.
(Additional reporting by John Irish in Paris; Writing by David Lewis and Joe Bavier; Editing by Catherine Evans)