Conservative Leader David Cameron pledged extra help for young families on Saturday, in a bid to improve his party's appeal to new mothers and fathers.

A leaked internal Conservative Party presentation, published on the Daily Telegraph Web site, said the party had to improve its credibility among families as polling showed people moved away from the Tories once they had children.

Cameron argued that preventing family breakdown and its attendant social costs would also have benefits for the wider economy.

"The reason ... tax bills are so high is that we are all paying the price of family breakdown and social failure," Cameron told Sky News at his party's spring conference in Gateshead..

"The reason crime is so high, the reason there is so much problem with drugs and alcohol and all the rest of it is because of family breakdown.

"So why not invest now to help families when kids are born, and help families stay together, because then we will actually be able to keep taxes and regulation down on a sustainable basis."

Later on Saturday Cameron will tell party activists that a future Conservative government would increase the number of health visitors in England by 50 percent to ensure that every expectant and new mother received regular support at home.

The cost of 4,200 more health visitors would be met by reallocating 200 million pounds of funds targeted by Prime Minister Gordon Brown's Labour government for extra "outreach workers" under its Sure Start programme of pre-school childcare.

"Money is tight and we have to make choices," Cameron will say.

"Instead of more untrained outreach workers, we need more trained professionals who really know what they're doing."

The appeal to young families follows a Tory commitment on Friday to allow new mothers and fathers to take time off work together after a birth to ease the burden of early childcare.

Cameron hopes the family friendly pledges will build on the boost his party received after its popular proposal last autumn to raise the threshold for inheritance tax to one million pounds.

The Tories are ahead of Labour in opinion polls but need to boost their support further if they are to have a hope of winning a majority at the next election, due by 2010 but possibly coming as early as summer next year.

Conservative Shadow Chancellor George Osborne said on Friday he would have little room for extra vote-winning tax cuts should his party win power because of the high level of government borrowing.

Osborne has committed himself to maintaining Labour's spending plans till 2011 should he become the next chancellor.