The Liberal Democrats will back stronger workplace rights for employees, party leader Charles Kennedy has pledged.

His statement came ahead of a groundbreaking speech to the TUC annual conference - in a sign of union discontent with the Labour leadership, Kennedy will become the first Lib Dem leader to address delegates when he makes a keynote speech on Wednesday.

And he appears set to take the opportunity to capitalise on Labour-union disagreements by focusing on how his party and the trade union movement share basic values in some key areas of concern.

But Kennedy denied any intention of trying to drive a wedge between Labour and its union allies.

"I am not going to the TUC to disrupt the party-union relationship, but to make my case," he said.

But he also suggested that Tony Blair's allies had been deliberately hitting out at union wreckers in an attempt to generate "favourable headlines in certain newspapers".

"There is a tendency in the government machine to tilt at the unions when the going is good. But the time may be fast approaching when they realise that goodwill and good sense from the unions is something they are going to need increasingly, never mind the cash contributions at election time," he said in an interview with the Guardian.

Kennedy said that he wanted improved worker consultation and stronger employment rights, taking the European social model and new European directives as his starting point.

"I find it a mystery why the government don't enthusiastically back these proposals from the EU. It will not put investors off."

He also argued that it was a breach of human rights for employers to be able to sack workers within eight weeks of a dispute.

"So long as a strike is lawful, the early sanction of dismissal does not accord with a country that has signed up to the European convention," Kennedy told the paper.

And he also aligned himself with the unions on another key issue, saying he was sceptical about the benefits of the government's use of private finance initiatives.

"I have a healthy scepticism about the PFI, because of the dangers in terms of long term payback and dangers to job security. But for a lot of councils it is left as the only show in town."