Canada's electronic spy agency has suspended sharing some of its metadata with its New Zealand counterpart and other partners in the Five Eyes alliance.
Metadata is information that describes other data - such as an email address or telephone number - but not the actual content of an email or phone call.
Government officials in Ottawa said some of the information it shared mistakenly contained personal details about Canadians.
Canada is part of the Five Eyes intelligence sharing network, along with the United States, Britain, Australia and New Zealand.
The country's Communications Security Establishment (CSE) agency had failed to properly disguise metadata - the numbers and time stamps of phone calls - before passing it on to the Five Eyes allies.
"CSE will not resume sharing this information with our partners until I am fully satisfied the effective systems and measures are in place," Defense Minister Harjit Sajjan said in a statement.
While the CSE is not allowed to specifically target Canadians or Canadian corporations, it can scoop up data about Canadians while focusing on other targets.
According to the annual report of its watchdog commissioner, the CSE had been using the information in a way that violated the country's defence and privacy acts.
However Mr Sajjan said the metadata Canada shared did not contain names or enough information to identify individuals. "The privacy impact was low."
He made the announcement shortly after an official watchdog that monitors CSE revealed the metadata problem.
The watchdog said CSE officials themselves had realised they were not doing enough to disguise the information they shared.
A United States National Security Agency (NSA) programme that "vacuumed up" Americans' call data was exposed publicly by former NSA contractor Edward Snowden in 2013, and prompted questions about other countries' practices.