A far-right extremist group has attacked a shared electorate office belonging to two National MPs, accusing one of them of being a "known Chinese Communist spy".

Action Zealandia, a relatively new group which mixes "European identity" politics with environmentalism and nationalism, uploaded photographs of the vandalism to its Facebook page on Friday.

They show members - faces blurred - sticking A4-size posters over the faces of list MPs Paul Goldsmith and Jian Yang on a sign outside their office in Epsom, Auckland.

The posters show a hand marked 'China' painting the Chinese flag over the New Zealand flag, with the phrase "Don't let them steal your country!"

The Facebook post said it was a message for "the traitors in Parliament".