Prime Minister Tony Blair has warned the world must "rid itself" of terrorist evil, following the bomb attack on a nightclub in Bali.

He was speaking as the death toll rose to at least 188, including 33 Britons.

Foreign Secretary Jack Straw said on Monday he was "as certain as he can be" that 18 British people have been killed in the Bali explosion - 15 are missing, believed to be dead, and 27 are injured.

Blair: 'We must combat the terror evil'

Mr Blair said the incident showed that the world was still under threat from terrorism.

Speaking from Downing Street, he said the attack was "evidence of the appalling depths to which these extremists will sink".

He added: "They are not worried in the least about the numbers of people they kill, about the total innocence of the people they kill.

"They are not interested in the destruction and devastation they wreak upon whole communities and families who have lost their loved ones."

UK terror attacks

11 September attack - 67 Britons killed Bali - 33 killed Omagh - 29 killed 1974 Birmingham pub bombing - 21 killed

Mr Blair said the response of the UK and its partners in the international community must be one of "total vigilance and total determination" to take whatever measures were necessary to prevent future attacks.

The Prime Minister is to make a more detailed statement to the House of Commons on Tuesday.

The Queen has also sent a message of sympathy to John Howard, Prime Minister of Australia.

Bomb carnage

Meanwhile, British tourists returning from Bali have been describing their terrifying ordeal following the nightclub bombing.

Three-quarters of the victims killed in the attack on a beach resort nightclub are thought to be Australians.

The Foreign Office said four Britons who were unaccounted for have since turned up safe and well in Bali.

Officials named one of the dead as Marc Gajardo, 30, from Cornwall. His relatives, who live in the Truro area, have been informed.

Nikki Bloomfield, 27, from Sunninghill, Berkshire, who returned to the UK from Bali on Monday, said she witnessed the carnage.

She said: "There were just people lying around with bandages round their heads and their legs, covered in blood."

Nikki Bloomfield saw the blast from her hotel

Seven Britons in a touring amateur rugby team from Hong Kong are feared dead.

The six men and one woman were last seen in the nightclub, a spokeswoman for the Hong Kong Rugby Football Union said.

The Foreign Office is urging people to avoid travelling to Indonesia.

The device exploded late on Saturday night outside a crowded nightclub in the resort of Kuta which is popular with foreign tourists.

While no-one has admitted carrying out the attack, Indonesian Defence Minister Matori Abdul Djalil said on Monday he believed it was linked to the al-Qaeda network.

Forensic teams

A team of British forensic and counter-terrorism specialists are on their way to Kuta to help with the investigation.

The Metropolitan Police said a team of officers from its anti-terrorist branch were also travelling to Singapore.

Detectives are appealing for information from anyone who has returned from Bali in the last few days.

Helpline numbers

British Consulate: 00 62 361270572 Foreign Office: 0207 0080000

The Muslim Council of Britain has strongly condemned the bombing and urged the authorities to punish those responsible.

UK tour operators are preparing to fly home some of the 1,000 British tourists who were on Bali, while holiday companies are arranging alternative destinations for holidaymakers booked to visit Indonesia in the coming days.

Keith Betton, from the Association of British Travel Agents, said he thought the explosion would not deter holidaymakers from visiting the region.

He said: "It could be a couple of years before the island recovers. But it will recover.

"I don't think people are going to be put off visiting Muslim countries.

The 24-hour telephone number set up by the British Consulate in Bali for people anxious about relatives or friends in Kuta is 00 62 361 270 572.