(Adds statement details, background)
LONDON, Sept 27 (Reuters) - Britain's prime minister DavidCameron pledged on Saturday to build 100,000 new homes and offerthem to younger first-time buyers at a 20 percent discount ifhis party wins a national election in May.
The extension of the ruling Conservative's "Help to Buy"scheme - meant to get people on the housing ladder - wasannounced on the eve of the party's annual conference, the lastbefore the vote.
Property is a politically potent issue in a country facing ahousing shortage that has helped push prices nearly 10 percenthigher nationally in the past year, and much more in London.
The "Starter Homes" plan, would only cover houses built onbrownfield sites, land which has already set aside forcommercial purposes, in England, the Conservatives said in astatement.
Buyers aged under 40 would get the discount on the marketvalue, made "possible because a Conservative government willexempt them from taxes, reduce development costs and allow therelease of cheaper brownfield commercial land to build thesehomes on," the party added.
The "Help to Buy" mortgage guarantee scheme was brought inlast year to help would-be buyers struggling to pay largedeposits. Some critics said it did nothing to spur new building.
A report by a former Bank of England policymaker publishedin March said the country needed 1 million homes. Constructionof homes in England slumped after the 2007-2009 financial crisisand is still struggling to recover. In 2013, 110,000 homes werebuilt, the second-lowest reading since records began in 1978 anddown from 177,000 in 2007.
Stewart Baseley, chairman of the Home Builders Federation,said the house building industry welcomed the Conservative plan.
"Enabling more first time buyers to realise their ambitionof home ownership and introducing policies that allow more landto come forward and increase house building would clearly bepositive," he said.
As deposits and property prices have risen, so too has theage of those entering the housing market. The average age of afirst-time buyer is 30 nationally, up from 28 in 2009. It is 32in London. (Reporting by Sarah Young; Editing by Andrew Heavens)