First-time buyers are among the hardest hit by housing problems

The party described its ideas as radical, and they include scrapping stamp duty on "principal" homes up to the average Welsh house price, which is currently £140,000.

Plaid will carry out a two-month consultation on its ideas.

But Labour claimed they were based on "spite" and Conservatives said they were "neither radical nor new".

The exercise, launched on Friday, will look at the reasons for the shortage of affordable homes in Wales.

As well as limiting stamp duty on main homes, Plaid also proposed imposing the highest level of stamp duty on second homes.

I will just wait to see if house prices go down but I've been waiting for the last year and I will be waiting probably for the next two First-time buyer Eurgain Williams

It also wants to suspend the right-to-buy scheme for council houses, encourage banks and building societies to offer shared equity mortgages, and set up a community land trust unit within the assembly.

This unit would help set up similar units in communities, which would then develop land for local use.

Elfyn Llwyd, MP for Meirionnydd Nant Conwy and Plaid parliamentary leader, said: "We need to look at the planning system - where (there are) developments of more than 10 houses, there should be a requirement for at least a third, maybe 40 per cent of these to be available for local people at reasonable prices.

"We would say we need planning permission if a property becomes a second home," said Mr Llwyd.

"And as a single bit of assistance to first-time buyers, the stamp duty system needs to be reviewed."

Hopeful first-time buyer Eurgain Williams, a 27-year-old teacher from Llansannan in Conwy, is looking for her first home, but could not afford to buy on her budget of £110,000.

Port Talbot recently topped a list of Wales' highest house price rises

"I was thinking I will just wait to see if house prices will go down but I've been waiting for the last year and I will be waiting probably for the next two years," she said.

"If the county council or community work together, and the assembly itself, to introduce a scheme that would be nice, not just for young people but local people as well."

Mr Llwyd attacked Labour's record on housing, saying the party had "done nothing in the last 10 years" about it.

But Labour Deputy Social Justice Minister Huw Lewis called Plaid's proposals "a housing policy based on spite".

"We are delivering policies designed to improve access to quality housing and to make it easier for the elderly and disabled to remain in their own homes," said Mr Lewis.

"Our social justice budget will increase by £150m over the next three years, with an extra £16m each year being allocated to the social housing grant.

"Sadly the nationalists believe that zealously punishing a single group of people will solve all of Wales' housing challenges."

Conservative social justice spokesman William Graham said the policies were "neither new nor radical".

"We need a wider consideration of affordable housing provision in Wales," he said.

"We need to ensure more effective co-operation with the voluntary and independent sectors - they are equally aware of the challenges we face and seek to participate in developing a solution."

Welsh Liberal Democrat housing spokesman Peter Black said: "Plaid need to go back to school on second homes.