Bahrain told a WTO meeting on Friday trade restrictions imposed on Qatar by Saudi Arabia, Bahrain and the United Arab Emirates were justified on national security grounds, a trade official who attended the meeting said.
Speaking on behalf of all three countries, Bahrain's representative told the WTO's Goods Council the measures were "in accordance with Article XXI of the General Agreement on Tariffs and Trade", which allows the usual rules to be broken for national security reasons, the official said.
Reuters could not immediately find any precedent in the WTO's 22-year history of a country explicitly and formally citing the "national security exemption" to pre-empt a potential trade dispute.
Some trade experts say that using national security as a defence risks weakening the WTO by removing the taboo and enabling countries to escape international trade obligations.
On Thursday the head of Qatar's WTO office told Reuters that his country was exploring all legal avenues to challenge the "blockade", including a complaint to the WTO.
He said that a national security defence could be challenged on the grounds of necessity and proportionality.
The feud erupted this month when Qatar's three Gulf neighbours, together with Egypt, severed diplomatic and travel links with Doha, accusing it of supporting terrorism and regional foe Iran. Qatar denies the accusations.
Qatar, which had asked for the issue to be discussed at the Council on Trade in Goods, following a similar debate at the Council on Trade in Services earlier this month, said the restrictions affected commercially important sectors such as aluminium.
The UAE's representative said there were treaties against the funding of activities that threaten other countries' national security, and warned against the WTO intervening in the matter, the official who attended the meeting said.
Egypt's representative also said the measures fell under "exceptional circumstances" and were therefore consistent with WTO rules.
A U.S. trade diplomat said that all parties should remain open to negotiations, the trade official said, and that the United States would not get ahead of current diplomatic discussions and would continue to support the mediation efforts of the Emir of Kuwait.
Turkey's representative at the meeting said Turkey hoped for a quick resolution, emphasising "hundreds years of fraternal and strong ties" among the countries involved.