THE United States and New Zealand ended a near 25-year break in intelligence collaboration last year but kept the news secret, according to a leaked cable published on Sunday.

The cable from the US embassy in Wellington was included in a package of secret documents released by website WikiLeaks and printed in the Sunday Star-Times.

Washington imposed strict restrictions on the supply of intelligence to Wellington in the mid-1980s in response to New Zealand's nuclear-free policy.

But according to a cable sent from the US embassy to US Secretary of State Hillary Clinton in January this year, collaboration was ''fully restored'' in August 2009.

Mrs Clinton was also warned the news ''should not be acknowledged in public''.