UNITED NATIONS, July 21 (Xinhua) -- UN Secretary-General Antonio Guterres remains deeply concerned by the continuing and expanding military escalation between Iran and the United States, said his spokesman on Tuesday.

Guterres is particularly concerned about attacks on civilian infrastructure in Iran, including a nuclear power plant under construction and a desalination plant, and also across the region, said Stephane Dujarric, the spokesman.

"We've seen attacks on power plants and desalination plants in Kuwait and other places. Such attacks are unacceptable and must stop immediately," he said.

Vital infrastructure on which civilians rely for survival, including hospitals and water supplies, must be spared. All parties must respect their obligations under international humanitarian law, including the principles of distinction, proportionality and precaution, said the spokesman.

The crisis has already affected Iran, Bahrain, Jordan, Syria, Iraq, Saudi Arabia, Yemen, Qatar, Kuwait, and the United Arab Emirates, placing pressure on trade systems, humanitarian access, transport costs, and the prices of fuel and basic commodities in those countries and beyond, he noted.

Guterres reiterates that there is no military solution to the current conflict, and calls for intensifying diplomatic efforts toward a peaceful and durable settlement, said the spokesman. ■