Attempts by tobacco-producing nations to sink Australia’s plain packaging law for cigarettes and cigars has picked up pace, as WTO members approved a broad probe on whether Canberra has broken the rules of global commerce.

Australia could learn by the end of the year whether its rules, which are widely praised by anti-smoking campaigners, fall foul of international trademark law.

Trade analysts say that whatever the result of the battle, it could have far-reaching implications for how governments balance global intellectual property rules with measures they say are in the public interest.

After facing off in Friday’s closed-door meeting of the World Trade Organization’s dispute settlement body, Australia and its adversaries – Cuba, the Dominican Republic, Honduras, Indonesia and Ukraine – agreed to fold five separate challenges into a single case, sources said.

WTO chief Roberto Azevedo is expected by May 5 to name the three-member panel of independent trade and legal experts who under the organisation’s rules will then have six months to issue a ruling.