The conflict is further complicating the situation in the region, Ignazio Cassis told Le Temps newspaper.

"If the goal was to resolve everything with an operation like the one in Venezuela, that hasn't been achieved," he said.

"And we risk getting involved in a war whose duration, intensity, and outcome are difficult to predict. There's also the escalation of the conflict across the entire region, the Middle East. This is precisely what Switzerland has always sought to avoid."

For decades, militarily neutral Switzerland has played a key role in maintaining basic diplomatic contacts between Iran and the United States.

In its role as the so-called protecting power, Switzerland has been representing US interests in Iran since Washington broke off relations with Tehran after the 1980 hostage crisis, a year after the Iranian revolution.

"The role of communication channel continues; it has not been denounced by either side. But currently, it does not apply, since communication is, unfortunately, carried out by force of arms," said Cassis.

US and Iranian negotiators held indirect talks on Tehran's nuclear programme, through Omani mediators, in Switzerland on February 26.

Two days later, the United States and Israel began their attacks on Iran. Tehran has responded by striking targets across the Gulf region and beyond.

Cassis said he had spoken with the negotiating parties on February 26.

"They all seemed to think we still had some time to reach a solution," he said.

"When progress is being made, you obviously can't be happy when a war breaks out just as you're making headway. History shows that most conflicts end up being resolved around a negotiating table."

Switzerland decided Friday it will not authorise the export of war materiel to the United States during the Middle East conflict, in line with its long-standing principle of military neutrality.

Switzerland has already refused US requests for flights over its territory since the war erupted.

"Before this decision, we had obviously contacted them," Cassis said.

"We explained that, given our neutrality, it wasn't possible to allow their warplanes to fly over our territory. But since the flyover only lasts a few minutes, they can easily find alternatives. So we weren't expecting a strong reaction."