Tony Blair has been joined by seven other European leaders in calling for the continent to unite in support for America's stance against Iraq.

After a difficult session of prime minister's questions during which he was periodically heckled by his own backbenchers, Blair held talks with Silvio Berlusconi, the prime minister of Italy, in Downing Street.

The prime minister, together with Berlusconi and the leaders of Spain, Portugal, Hungary, Poland, Denmark and the Czech Republic, has signed an article in today's Times calling for cohesion and unity in Europe.

The article, published by newspapers across Europe and masterminded by Spain and Britain, says: "We cannot allow a dictator systematically to violate these resolutions. If they are not complied with, the security council loses its credibility and world peace will suffer as a result.

"We are confident the security council will face up to its responsibilities."

In response to jibes from Labour backbenchers, Blair had earlier revealed that "after we deal with Iraq", North Korea and other countries possessing weapons of mass destruction would have to be dealt with.

After another MP said "Where does it stop?" Mr Blair replied: "We stop when the threat to our country and security is properly dealt with."

The prime minister will today head for Madrid for talks with the Spanish prime minister, Jose Maria Aznar, before tomorrow flying to the United States for a summit with president Bush at Camp David.

The United States alleged yesterday that Iraq has been spying on United Nations weapons inspectors.