UN Secretary-General Antonio Guterres on Monday called on “all parties” to respect freedom of navigation in the Strait of Hormuz, after Iran and subsequently the United States blocked flows through the critical waterway, reports AFP.

The strait, through which a fifth of global oil and gas flows, has become a key flashpoint as the US and Iran attempt to gain leverage over each other during ceasefire negotiations.

Disruptions in the strait “have already had direct effect well beyond the immediate region, with increased global economic fragility and insecurity in many sectors,” the UN chief’s spokesman Stephane Dujarric said in a statement.

The remarks came after US President Donald Trump ordered a blockade of ships entering or leaving Iranian ports and coastal areas on Monday, following the failure of peace talks over the weekend.

Iran had already effectively halted traffic through the strait following the US-Israeli attacks beginning February 28.

“We need to remember that some 20,000 seafarers have been caught up in this conflict and are currently stranded on ships, facing increasing hardships daily,” Guterres’ spokesman also said.

Guterres also called for peace talks to continue.

“At the same time, the ceasefire must absolutely be preserved. All violations must cease,” the spokesman said.