Liberal Democrats will not necessarily support spending more cash on public services than the government already plans, their party leader has said.

In an interview with ePolitix.com, Charles Kennedy said his party's approach would be based on different ways of raising and spending the money, rather than criticising the levels of investment announced in Gordon Brown's three-year spending review.

"On current projections, we support the sums Labour are investing," the Liberal Democrat leader said.

"We don't share the Conservative view that they should be opposed. Our criticism is not so much 'Should we spend more, or should we spend less?' - it's that we would spend it differently and we would raise it differently."

Kennedy said his party would adopt a more transparent approach to income tax and other taxes earmarked for specific uses. "This is a major policy difference between all three parties," he added.

The Lib Dem leader said that while ministers should be accountable for the sums earmarked for their departments, there was also a "glaringly absent" sense of accountability to local people.

"We would like to see all that being put on a much more democratic footing. Gordon Brown has announced a whole plethora of quango-like mechanisms that will come into being to police the police, to police the schools, to police the hospitals," he said.

"But it does rather beg the question 'who polices them?'. That I think is the democratic deficit at the heart of it all."

On the NHS, he said it was "highly unlikely" that his party would come out in favour of charges for non-essential minor operations.

Kennedy predicts future success for his party, saying its policies are backed by the public.

"We've now got that credibility factor. People are not now going around saying the Lib Dems will be back to a couple of dozen seats after the next election. They are assuming that where we're at is a staging post for something else," he said.

"That makes it a lot more intriguing and enjoyable for me personally - but it also makes it a lot more unpredictable. Once you cross that credibility barrier with the public then really anything can happen - particularly with as distortive a system as first past the post."

And after a recent media spat over a BBC interview in which he was questioned about his drinking habits, the Lib Dem leader said he had proven his mettle during the general election campaign.

"The truth of the matter is - when you're leading a political party - more than anything else what you need is a general election under your belt. Until you've fought a battle, people can't really judge how good a soldier you are. I've got that behind me and I think it's generally perceived to have gone pretty positively for the Lib Dems and for myself," he said.

Questioned about the government's emphasis on "hard working families", Kennedy said he had "no disagreement" with the basic approach.

"I have no complaints about seeking to promote good support for families - but we shouldn't at the same time over-neglect the other predominant groups in society that are with us to stay," he said.

Kennedy also defended his decision to break Cabinet-level links with the Labour Party, saying they now had "more room and freedom politically as a party".

"It also means that, unlike when I was first elected leader, I no longer spend two thirds of every interview I do talking about how close or far away I am from Tony Blair or from the Labour government this week compared with last week. People are actually questioning us on our policies. So that has all undoubtedly been to our benefit.

"But - having said that - if Tony Blair were to come on the phone just now and say 'I've decided that we want to look again at proportional representation' - I'd quite happily go along and have a meeting about that. But it's not likely. I'm not sitting here on tenterhooks waiting for the phone to ring," he said.

Kennedy added that the only likely area for future cooperation might be Labour's election pledge to review the various voting systems in use in the UK.

"But there has not even been the initial discussion yet about what shape or form that might take. I strongly suspect that they have not even got round to thinking about it yet."

On campaigning for next year's Scottish parliament elections, he said he would be "heavily involved".

"Jim and I discussed this a few weeks ago in-depth. He's keen for me to play a prominent role and I'm keen to be involved. But at the end of the day, he's the head guy in this context. He's the leader of the party in Scotland, he's the deputy first minister. But I will be there to roll up my sleeves as required."

Kennedy also takes a swipe at Conservative leader Iain Duncan Smith, saying that after his first year as Tory leader it is "quite remarkable that he hasn't made more of an impression".