Ministers are failing to implement David Cameron's own test to protect families, despite his insistence "the answer should always begin with family", according to a new report.

The report published on Tuesday revealed 10 out of 14 relevant departments could show no evidence where the Prime Minister's much heralded "family test" had been applied. It shows a variation in the appetite of ministers to apply the test, which was announced by Cameron in 2014.

The Department for Work and Pensions leads on the issue and has produced seminars to help other departments follow suit. However Business, Education and Defence were the only other departments able to point to instances where it had been applied.

The test is one part of Cameron's claim to run a compassionate Conservative government and he has frequently spoken of families as essential to fight poverty. In one speech he said: "From here on I want a family test applied to all domestic policy. If it hurts families, if it undermines commitment, if it tramples over the values that keeps people together, or stops families from being together, then we shouldn't do it."

However a group of charities working with families said the response of ministers was "patchy" and a "concern".

"The majority of departments have shown limited commitment to implementing the family test," says the report.

"It is clear that the Family Test is not, as yet, meeting the Prime Minister's commitment that it should be applied to all domestic policy."

The charities called for the family test to become a legal requirement when developing policy and say departments must publish their assessments in the interest of transparency.

Chief executive of the Family and Childcare Trust, one of the charities involved, said the family test was a "flagship government policy" but it was "clear" minister have not applied the test across all policies.

Nola Leach, CEO of Christian policy charity CARE, said the family test was an "innovative and bold concept" but said the lack of implementation was "very disappointing".

"If the Family Test is to become the powerful tool it should be in helping to safeguard family life it needs to become part of the culture of policy making across Whitehall," said Leach.

"Families are the very best safety net we have and given the cost of family breakdown is a colossal £47 billion a year, robust action is clearly needed."

CARE has campaigned for the family test to become statutory. The charity said it "wholeheartedly endorsed" the report's recommendations.