The report identifies ways of plugging the childcare gap

The idea was included in a survey of parents' attitudes to childcare, commissioned by the executive.

The survey said "informal" childcare providers, such as relatives or friends, could be offered training to improve the quality of care.

A spokesperson said the executive did not want to "over-regulate" informal care and risk creating "a nanny state".

Flexible employment

The survey called for a "coherent national policy" on childcare.

It said: "The greater use and preference for informal childcare suggests that at least part of the focus of policy must be on assisting informal provision.

"Informal providers could be offered some basic childcare training and more flexible employment or benefits packages to try and develop more quality informal childcare."

Formal childcare providers, such as childminders, could be offered training programmes, subsidies or relocation packages to enable them to improve their services, broaden their market base and reduce the overall cost of childcare.

And individual groups, like working lone parents, could be targeted to receive formal childcare vouchers.

Our priority is to focus on people involved in formal childcare. A Scottish Executive spokesperson Your views: What role should grandparents play?

However, the executive ruled out the plan to train grandparents.

Its spokesperson said: "We are very clear that we don't want to over-regulate the sector, particularly on informal arrangements.

"It would almost be the nanny state, to coin a phrase, if we were to start telling parents what sort of informal childcare arrangements they can or cannot have.

"Our priority is to focus on people involved in formal childcare."

The survey found seven out of 10 parents agreed there should be more nursery education places for pre-school children, and more supervised places for school-age children to go outside school hours.

Good quality childcare

More than half the parents questioned agreed that if they could afford to give up full-time work, they would prefer to stay at home and look after the children.

But a fifth of parents said they would work more hours if they knew they could arrange convenient and good quality childcare.

Maureen O'Neill, director of Age Concern Scotland, said that childcare provision and formal training should be all about choice.

She told BBC Radio Scotland: "If a parent chooses their mother or mother-in-law to look after their child, it is because they have trust and faith in them.

"If you start to train people, you're formalising it in a way that maybe not everyone wants but that some people might appreciate. It's not a black and white issue."

However she added that if childcare was made more formal with training in place, recognition and reward for those looking after children should follow.