One of Wales' biggest teaching unions has said more than 200 schools should close - because they are too tiny to teach the National Curriculum properly.

NASUWT Cymru has suggested that schools with less than 50 pupils are too small to cope with teaching demands.

The union has argued that teachers in rural areas of Wales are overstretched and that small schools fail to offer a full educational experience to pupils.

We need to forget about sentiment and emotion and to think purely in educational terms

Union leader Geraint Davies

Campaigners have launched fierce fights to save their village schools, but Geraint Davies of NASUWT Cymru believes they are fighting a losing battle.

"As far as the NASUWT is concerned this is a burning question," he told BBC Wales.

"Are these small schools economically and educationally viable?

"I have to say the answer to both is no.

Geraint Davies: 'Intolerable demands'

"We need to forget about sentiment. We need to forget about emotion and to think purely in educational terms."

Across Wales there are currently 218 small schools with less than 50 pupils each - the majority serving rural communities.

Excluding special schools and newly-opened Welsh small-medium schools, Ceredigion has the most with 42, Gwynedd has 36, Carmarthenshire has 28, and Powys 27.

Mr Davies said the "intolerable demands" of the National Curriculum meant that, in some cases, their teachers had to deliver 33 subjects across three different age ranges at primary level.

There were protests in April at closure plans

"It's a nightmare and no teacher should face that in this day and age."

He also said the children were missing out on important opportunities such as being able to compete in a school football, netball or rounders team because the school roll was so small in many schools.

Education authorities in the areas are trying to rationalise the number of small schools by creating larger area schools to serve wider areas.

Most of the schools were built in the Victorian age, many do not have an assembly hall, and some are still using outside toilets.

Ysgol Dinas: closure threat

The cost of keeping small schools open is also high.

Pembrokeshire Council says it cost �6,000 to educate each child at Dinas on the north coast - which is under a current closure order - compared with a countywide cost of �2,000 per child.

According to Mr Davies, many parents are "voting with their feet" by transporting their children to larger schools a few miles from home.

"They are bringing their children to the nearest village for the simple reason it is a larger school and offers wider opportunities to their children."

Nevertheless, campaigners fighting to keep these smaller schools open maintain their children are getting the best education.

In April Welsh Education Minister Jane Davidson announced she was making �2m available to boost rural and village schools.

All counties would benefit under the scheme.

However, the largest sums were to go to rural authorities such as Carmarthenshire, Powys, and Gwynedd.