The "modernised" scheme will cover those whose tenancy begins from Monday onwards.

The length of time a person will have to live in a property before they can buy it is extended from two year to five years.

The maximum discount on the purchase of a tenant's home will be halved to 35% or �15,000, whichever is the lower figure.

We are calling for the Scottish Executive to make adequate money and resources available to ensure homeless and badly housed people reap the rewards from the new laws

Gavin Corbett Shelter Scotland

Housing associations have also been given up to 10 years' exemption from the right to buy.

However, this will not affect housing association tenants who have an existing right to buy their home.

Social Justice Minister Margaret Curran said the move "restores the balance between those wishing to buy and those wishing to rent".

It is only one of the provisions in the 2001 Housing (Scotland) Act, which takes effect from Monday.

Ms Curran described it as "one of the most significant pieces of housing legislation in Scotland for a generation".

Consult tenants

She said: "The provisions which are coming into force today will make a real difference to the lives of tenants throughout Scotland by better balancing their rights and bringing council and housing association tenants under the same tenancy agreement.

"They will also ensure that landlords consult their tenants on decisions affecting them," she said.

More than 700,000 housing association tenants will now have the same tenancy agreement as those living in council housing under the Scottish Secure Tenancy (SST).

Margaret Curran: "Make a real difference"

In addition to improved rights on joint tenancies and succession, it means that registered social landlords must provide compelling evidence to obtain a court eviction order.

Councils are also given a duty to offer accommodation, whether permanent or temporary, to all homeless people, while putting the needs of children at the forefront.

Scottish National Party social justice spokesman Kenny Gibson said his party welcomed the increased role for housing associations in providing accommodation for homeless people.

"One of our concerns is that since New Labour came to power, resources to public sector housing have declined by 30%," he said.

"While we can impose duties on organisations, adequate resources must be provided to ensure the legislation achieves its aims - one of which must be to reverse the decline in decent, affordable, public housing across Scotland."

New rights

Shelter Scotland's head of campaigns, Gavin Corbett, said: "We are calling for the Scottish Executive to make adequate money and resources available to ensure homeless and badly housed people reap the rewards from the new laws."

The organisation has launched a programme to ensure that the homeless are aware of their new rights.

Nick Fletcher, policy officer for the Chartered Institute for Housing in Scotland, said the new SST would end confusion over tenancy rights in the social rented sector.