An airline passenger data-sharing deal between the EU and Canada - which supporters say is vital to fighting terrorism - is in jeopardy after a legal adviser to the EU's top court concluded the agreement was too invasive and violated people's privacy.

Advocate General Paolo Mengozzi said parts of the 2014 agreement, which has yet to be ratified, should be reworked because they violate the EU Charter of Fundamental Rights. The court is not obliged to follow such recommendations, but it often does.

Mengozzi's opinion could have global consequences, as governments around the world have reiterated the need for greater data retention and sharing after a series of deadly attacks by militants this year.

EU lawmaker Timothy Kirkhope, who steered so-called Passenger Name Record (PNR) legislation through the European Parliament in April, called Mengozzi's opinion "irresponsible," citing the elevated security threat.

Canada accepted the "detailed opinion" and said it would cooperate with its European partners to find an acceptable compromise.

"We remain committed to continue working closely with the European Union until the ratification of a Canada-EU PNR Agreement that complies with EU fundamental rights and EU law," a government representative said.

EU court still to decide

Mengozzi is one of 10 advocates general who provide legal opinions to the EU court, which is expected to take several more months before issuing its definitive opinion.

The advocate general said a few modifications could make the agreement compatible with EU law. That would include not collecting sensitive data, clearly listing the offenses for which data can be retained and limiting the number people who can be targeted to those who can reasonably be suspected of engaging in terrorist activity.

Mengozzi's conclusions could also bode ill for a separate data transfer agreement with the United States. The EU-US Privacy Shield, which was adopted by the European Commission in July replaced a framework agreement that was rejected by the European Court of Justice last year over fears of mass US surveillance.

Privacy advocates are expected to challenge the agreement.

Civil rights groups and liberal politicians welcomed Mengozzi's opinion, maintaining that it's important to protect privacy rights even when facing security threats, according to Dutch Member of the European Parliament, Sophie In 't Veld.

"For years now," she said, "we have questioned the necessity and proportionality of a massive transfer of European passenger data and the legal basis for this."

bik/kl, jbh (Reuters, dpa)