Paris under attack: World tightens security

Few countries urge citizens not to travel to France

World leaders responded to the bloody attacks in Paris with outrage and defiant pledges of solidarity, but several countries said they would tighten security, especially at their borders, and a few urged their citizens not to travel to France.

Several countries said they had stepped up their own security in response to the attacks, including Belgium and Switzerland, which border France. France's neighbour to the south, Spain, said it was maintaining its state of alert at level 4 on a five-point scale.

Dutch Prime Minister Mark Rutte said the Netherlands would tighten security at its borders and airports, and said the Dutch were "at war" with Islamic State.

New York, Boston and other cities in the United States bolstered security, but law enforcement officials said the beefed-up police presence was precautionary rather than a response to any specific threats. The Unites States and Russia, divided on many issues including the war in Syria that has fuelled Islamist violence, voiced their support for the French people on Friday night.

"Once again we've seen an outrageous attempt to terrorise innocent civilians," US President Barack Obama said. "We stand prepared and ready to provide whatever assistance that the government and the people of France need."

British Prime Minister David Cameron said the threat to Britain remained "severe" after the Paris attacks, as a terminal at a major UK airport was evacuated as a precaution amid heightened security fears. Cameron did not raise the threat level to its highest "critical" level, which would have meant an attack is expected imminently, after discussing the attacks at an emergency response committee in London. "The threat is already at 'severe' which means an attack is highly likely and will remain so," he said in a televised address on Saturday.