Experimenting: Liberal Democrats Mike German and Kirsty Williams

The party, which has been in coalition with Labour in the Welsh Assembly Government for two-and-a-half years, used a university laboratory for its manifesto launch to claim that it could "deliver the difference".

Its 12,000-word manifesto contains more than 300 pledges.

Mike German, leader of the Lib Dems in the assembly, said: "If you really want to make a difference to people's lives, these are the things we think are important."

But he would not say with which Labour policies he disagreed. Labour has announced 10 main pledges - such as free breakfasts in primary schools - in advance of its full manifesto on Wednesday, and Mr German had said he would give his response then.

Main meal

"It seems to me they've grabbed the opportunity to give you a little snack before we get the main meal," he said.

But Kirsty Williams, the party's health spokeswoman, said the Labour proposals announced so far were "very populist" and were hoping to take attention away from some of its difficulties.

Our vision is of a Welsh education system which leads the world Lib Dem Mike German

She said Labour had not yet given any substantial pledge on how to solve the problems in the National Health Service.

The Lib Dems - who are known for their camera-friendly election stunts - offered a typical photo-opportunity to emphasise the impact they say they have had on the assembly government and on life in Wales.

'Clear Welsh water'

The party staged its launch in a chemistry laboratory at Cardiff University.

Its mixed red, green and blue liquid - signifying Labour, Plaid Cymru and the Conservatives respectively - with the "clear Welsh water" of government to show the limited effect the other parties have had.

But when a concoction in Lib Dem yellow was added, it fizzed up spectacularly. The point was made, although a smiling Mr German was quick to deny that this implied his party amounted to froth.

The Lib Dem pledge on free care for the elderly is to extend it "so that as few people as few possible have to pay for care in old age."

Lib Dem manifesto pledges Free care for elderly Classes 25 and under Free leisure for young No top-up fees for students 'Fair voting' for local councils

The party also wants no child to learn in a class bigger than 25. This is an extension of an existing target during the next four years to cut all primary schools classes to 25 or under.

Mr German said pupils should have the best possible environment for learning. "Our vision is of a Welsh education system which leads the world," he said.

Referendum

The other top pledge would not mean free entry to leisure centres for the under-16s at all times, however.

The Lib Dems said they recognised, for instance, that there should be periods set aside for older people, and that leisure centres would not always have the space to let children in for nothing.

Other main pledges included the abolition of upfront tuition fees, a "fair voting system" - in other words, proportional representation - for elections to local councils, and for the assembly to become a senedd - or parliament - with law-making powers.

The Lib Dems also wanted this senedd to have tax-raising power of up to 3p in the pound - but only if it was approved in a referendum of the people of Wales.