The prime minister has slammed the Conservative campaign on asylum, describing Michael Howard's policies as "an incoherent babble".

Visiting Dover, at the front line in the battle to secure Britain's borders, Tony Blair called for the issues of immigration and asylum to be kept "in perspective".

"Concern over asylum and immigration is not about racism, it is about fairness," he said, accepting that the public wants to see action.

"We do get it. We are listening," he said. "We know we have to tighten the asylum system further."

"We will put in place strict immigration controls that work," Blair pledged.

"I never want this issue to be one which divides our country, which sets communities against each other.

"We are a tolerant, decent nation. That tolerance should not be abused, but neither should it be turned on its head."

He added that genuine asylum seekers should be welcomed and those needed for the economy should be allowed in, while those who stay illegally must be removed.

Tory plans

Turning his fire on the Tories, the prime minister criticised their high profile campaigning on the issues.

He said the issues should "never be used as a political weapon, an instrument of division and discord".

Blair said Britain's diversity was "a source of strength, not weakness".

And he added that Tory policy on asylum is "frankly a joke, an incoherent babble", while their immigration plans were "meaningless".

But Blair accepted the issue was "hard to tackle". He added: "It is part of a modern, changing world."

The prime minister said he had lost count of the number of meetings he had chaired on the issue.

Earlier, home secretary Charles Clarke detailed an expansion in the number of border guards.

"Today I am announcing that early in the next parliament we will appoint another 600 border guards in this country, an increase of one in eight, a very significant increase on what we inherited from Michael Howard," he said.

Targets

Blair said that new technology, including identity cards, would help to tackle the problems in future.

He said a third term Labour administration would introduce fast-track processing and removal of unfounded asylum applicants, with more detention and tagging.

The prime minister said a target would be set that removals should exceed the number of asylum applications.

And a points system would regulate the immigration system to ensure the people allowed to stay are "the people we need".

Exploitation

Blair said that words on asylum "are easy" but cautioned that "change is tough to bring about".

"Frightening people is easy. Fighting problems is tougher," he said.

"We should never ignore this issue but we should never exploit it.

"We should deal with it. We will deal with it calmly, sensibly, reasonably, in the best traditions of Britain."

Contribution

The prime minister praised the contribution of immigrants to British society,

"I think most people know the huge contribution immigrants have made to our economy," he said.

Blair added that they contributed to "the rich fabric of our nation".

"They are every bit as British and valued as any other member of our society."

Political issue

Shadow home secretary David Davis said the speech showed that the prime minister was "rattled".

"We've heard it all before. He's spent years pussyfooting around this issue, during which time our asylum and immigration system has become chaotic and out of control," Davis added.

"Today, Mr Blair said next to nothing about the quarter of a million failed asylum seekers currently in the country, illegal immigration and the fact that immigration has tripled.

"There is a clear choice at the next election: limited and controlled immigration with the Conservatives, or unlimited immigration with Mr Blair and the Liberal Democrats."

Meanwhile Liberal Democrat leader Charles Kennedy refused to be drawn into attacking the Tories.

"On offer from the political parties is something of a consensus that we need a responsible, controlled immigration policy. That's what we are putting forward," he said.