The provision of services for children with speech difficulties is "highly unsatisfactory", according to a report by Conservative MP John Bercow.

The MP published the interim findings of his government-commissioned review looking at services for under-19s who have communications difficulties, ranging from a mild stammer to problems connected to autism or cerebral palsy.

The report said the current system is "patchy", and in effect, "a postcode lottery".

While the number of speech and language therapists has increased by more than a third between 1997 and 2006, the report said, many families still find it difficult to get continuous support.

Bercow said: "Although there are some skilled professionals and very good facilities, the overall position is highly unsatisfactory.

"Access to information and services is poor, services themselves are very mixed, continuity across the age range is lacking, effective joint working between the health and education services is rare and there is something of a postcode lottery across the country.

"Above all, local commissioners attach a low priority to the subject and this must change."

His final report is expected in July this year.

Health secretary Alan Johnson, who joined Bercow and children's secretary Ed Balls to launch the interim document, said: "Over the last 10 years, we have increased the number of speech and language therapists and worked hard to improve access to professional programmes to help children overcome early speech problems.

"But we recognise more needs to be done."

Bercow, the MP for Buckingham, has an interest in special needs education and is chairman of the all-party parliamentary group on speech and language difficulties.

The prime minister recruited Bercow, along with another Tory MP and a Liberal Democrat member, to conduct reviews soon after taking power last year.