SEMAISIMA: Qatar inaugurated its largest coast guard base Sunday as a standoff between Iran and the United States continues to boost tensions in strategic Gulf waters.

Prime Minister Abdullah bin Nasser bin Khalifa Al-Thani and commander of US Naval Forces in the Middle East Vice Admiral Jim Malloy attended the ceremony at the Al-Daayen naval base in Semaisima, 30 kilometres (18 miles) from Doha on Qatar's eastern coast.

Qatar, a key US ally in the region, is home to Washington's largest Middle East military base.

Malloy, commander of the US Fifth Fleet based in Bahrain, said the new base was "a wonderful opportunity for us to interface more strongly with the Qatari coast guard".

Tensions in the Gulf -- through which nearly a third of the world's oil is transported -- have spiked in recent weeks, with the US blaming Iran for multiple attacks on tanker ships in the region and Tehran shooting down an American drone.

The 600,000-plus square-metre site aims to "facilitate the securing of all territorial waters of the State and border posts", the interior ministry wrote on Twitter.

It includes a "sophisticated seaport", training and medical facilities, civil defence offices and operating rooms, the ministry added.

Asked whether the base could enhance US-Qatari coordination on Iran, Malloy said the move was "all about maritime security, that's what our focus is".

The US said Thursday it was discussing military escorts for vessels in the Gulf a day after armed Iranian boats allegedly threatened a British oil tanker in the Strait of Hormuz.

And on Friday Britain said it was sending a second warship to the Gulf and raising the alert level in the oil-rich region after Iranian gunboats threatened a UK supertanker. —AFP