Developing his strategy of attacking the Tory government while marking out territory distinct from Tony Blair's New Labour Party, Mr Ashdown laid claim to the "true patriotism" of tolerance and international co-operation.
He told his party's parliamentary candidates at Westminster last night that the Tories were "abusing patriotism in a desperate attempt to cling on to power, but it is a false patriotism".
He attacked the growing questioning in the Tory party of Britain's membership of the European Union. "It is now the voices of isolationism, even of a petty xenophobic nationalism, that are the loudest ones we hear," he said.
"We are told that all this unpleasant hysteria is about patriotism, that it is all about standing up for Britain. Nothing could be further from the truth."
He said: "Britain's greatness has not come from looking inward, from retreating behind island walls or shouting insults at foreigners. It has come from going out, making things happen, building empires, interacting with other cultures".
He went on: "English, as a language, did not flower through mean Anglo- Saxon monosyllables, tailored for the front page of the tabloids. It flowered from the words of Milton and Shakespeare, which drew so richly on the classics and on the treasury of European tongues.
Mr Ashdown laid down a challenge to Labour by positioning the Liberal Democrats as the most libertarian party on race and immigration.
He then attacked Michael Howard. "A true patriot would be repelled by a Home Secretary pandering to racism, xenophobia and intolerance," he said.
He said a true patriot would oppose the Asylum and Immigration Bill, which Mr Blair and Jack Straw, Labour's home affairs spokesman, have made clear they will not vote against.
"A true patriot would condemn out of hand this tawdry affront to our centuries-old tradition of tolerant welcome for the persecuted - Dutch Protestants, French Huguenots, Jews from all over Europe, and many, many others," he said.
His speech follows the challenge last week from Alex Carlile, Liberal Democrat home affairs spokesman, to Mr Straw, after Labour failed to support his amendments to the Bill in the House of Lords: "Whose side are you on, Jack?"
Mr Ashdown declared: "It is time for all true patriots to argue with passion again for the traditional values of decency and tolerance at home, for reform in our rotten politics, for constructive co-operation abroad."Reuse content