PARIS: A violent mob torched at least three churches in Niger's capital Niamey Saturday during fresh protests against Charlie Hebdo magazine, as France's president stressed his commitment to “freedom of expression".

Around 1,000 youths wielding iron bars, clubs and axes rampaged through the city, hurling rocks at police who responded with tear gas in a second day of violent demonstrations against the satirical magazine's publication of the prophet Mohammad (PBUH).

The French embassy in Niamey urged its citizens to stay at home, the day after a rally against Charlie Hebdo in the country's second city of Zinder left four dead and 45 injured.

“Be very cautious, avoid going out,” the embassy said on its website as rioters also ransacked several French-linked businesses, including telephone kiosks run by Orange.

In his first reaction to the violence, which also erupted in Pakistan on Friday, President Francois Hollande stressed on Saturday that France was committed to “freedom of expression.“

Some 15,000 people also rallied in Russia's Muslim North Caucasus region of Ingushetia against Charlie Hebdo, which depicted on its most recent cover a weeping man holding a “Je suis Charlie” sign.

'They have to be punished'

Meanwhile, jittery European nations stepped up security in the wake of last week's attacks in France that claimed 17 lives, including 12 at Charlie Hebdo's offices.

Belgium began deploying hundreds of armed troops to patrol the streets after security forces smashed a suspected Islamist “terrorist” cell planning to kill police officers.

And in London, authorities were mulling “further measures” to protect police “given some of the deliberate targeting of the police we have seen in a number of countries across Europe and the world,” said Mark Rowley, head of counter-terrorism for the British police.

British police officers, for the most part unarmed, might be equipped with taser guns as part of reinforced security measures, according to the local press.

Traffic was suspended in the Channel Tunnel between France and Britain after smoke was spotted, but there was no immediate indication if there was a link to recent attacks.

French and Belgian authorities were grilling suspected accomplices both of the Paris gunmen and the alleged “terrorist” cell raided in eastern Belgium.

Belgian police were hunting for the suspected mastermind of the cell, a notorious 27-year-old jihadist who spent time in Syria and who may have prepared the foiled attack from bases in Greece and Turkey, according to local media.

Asked about protesters who burned the French flag, Hollande said: “They have to be punished because when it happens in France, it's intolerable, but also abroad. “

“I'm thinking of countries where sometimes they don't understand what freedom of expression is because they have been deprived of it. But also, we have supported these countries in their fight against terrorism,” said Hollande as he toured a market in his heartland of Tulle, central France.

Secret burial

Said Kouachi, one of the jihadist brothers who gunned down 12 people at Charlie Hebdo's offices before being cut down by security forces in a siege, has already been buried in secret, it emerged on Saturday.

He was buried Friday in the eastern city of Reims, where he lived for around two years, under heavy police protection and with a handful of family members present, according to a well-informed source.

His grave was unmarked and the name of the cemetery not divulged. His brother Cherif was expected to be buried soon in the Paris suburb of Gennevilliers.

The mayor of Reims, Arnaud Robinet, said he was forced by law to accept the burial but was initially opposed to the gunman being buried in his city.

He feared “a tomb that could become a shrine for people to gather around or a pilgrimage site for fanatics. “Said Kouachi's wife decided not to attend the burial, in order to keep it secret, said her lawyer Antoine Flasaquier.

“She is now relieved that her husband has been buried with discretion and dignity,” said the lawyer. Charlie Hebdo, which has flown off the shelves in record numbers since the attacks, announced on Saturday it would extend its print run to seven million copies.

Before the assault on its Paris headquarters, Charlie Hebdo had a circulation of around 30,000, with only a handful being sold abroad.

Touring the cheese and meat stands in the Tulle market, Hollande urged his locals to pick up where they left off before the worst attacks on French soil in half a century.

His visit was “a message to show that life goes on, that we have come through the ordeal with a great deal of dignity and efficiency. “

“We are of course aware that there are still threats ... there were arrests that were carried out in the past few days, but life has to go on and we even need to emerge stronger. “ “That's the best response we can give. “