Labour plans to slash affordable rents and give first-time buyers exclusive rights to purchase new-build homes for six months, it will announce this weekend, as it bids to steal the Conservatives’ claim to be “the party of homeownership”.

Lucy Powell, shadow housing secretary, will say a government led by Keir Starmer will restrict to 50% the number of properties in a development that can be sold to overseas buyers, which in some city locations has created “ghost towers” as investors leave homes empty. Labour also wants to give councils powers to force landowners to sell vacant sites to build new housing at lower prices than the compulsory purchase system currently allows.

The policy package will be announced at Labour’s conference in Brighton and amounts to a direct challenge to Michael Gove – the secretary of state for levelling up, housing and communities. Labour claims his decision to pause unpopular planning reforms has left the government without a strategy for meeting its housebuilding targets.

Labour is also keen to capitalise on what it perceives to be government weakness over its handling of the building safety crisis with hundreds of thousands of leaseholders, including people in shared ownership affordable housing schemes, facing bills in the tens of thousands of pounds.

“Labour is the party of homeownership, the Tories are the party of speculators and developers,” Powell said. “They treat housing as a commodity, not the bedrock of stable lives and life chances.”

But the Conservatives are also poised to make changes to housing policy, starting with reissued planning reforms. Putting Gove in charge of levelling up and housing policy has been widely viewed as Boris Johnson giving one of his most trusted ministers the remit for issues seen as crucial to the next election.

A lack of access to affordable housing is viewed as a key driver of inequality, both between regions and across generations. One of Gove’s new junior ministers is Neil O’Brien, the Tory MP who previously acted as Johnson’s official adviser on levelling up. He proposed reforming compulsory purchase powers for councils in a 2018 paper on solving the housing crisis titled “Green, pleasant and affordable”.

Labour also believes reform of compulsory purchases is crucial to reinvigorating beleaguered town centres, not least in northern constituencies which the party lost to the Tories in recent years, so that vacant shops can be brought back into use, including as affordable housing.

Powell is expected to say in a speech on Sunday that the link between work and affordable and secure housing is broken for too many renters and first-time buyers. By cutting the cost of affordable rents people will be able to save more if they wish to get on the housing ownership ladder.

Currently the definition of an affordable rent in many places includes properties which cost up to 80% of market rents. Under Labour, this would be cut to about 30% of average household income.

The Home Builders Federation said Labour’s policies giving priority for first time buyers and reducing affordable rent were workable, but it said the “first dibs” policy on new homes must only apply to cheaper properties and be “done in a way so that builders don’t lose out in a competitive market”.

It said cutting affordable rent levels could change the amount of housing that a developer could afford to build. As a result local authorities might allow different types of development that also contribute to meeting targets for affordable housing but are not affordable rent.