In the midst of a housing shortage, it's been revealed six out of 19 recently build state houses in Christchurch have been found to be contaminated with P - and the Labour Party is demanding answers.

This comes as news Housing New Zealand faces a nationwide $12-$13 million P contamination clean up bill this financial year.

Labour's Canterbury Spokesperson Megan Woods said Christchurch can't afford any housing offline.

"We are so short of housing, we need to ask some questions about what the screening process is."