Oil prices rose to their highest in almost six weeks on Wednesday, with Brent crude surpassing $95 a barrel, on mounting concerns about disruptions to Middle Eastern supply routes because of escalating hostilities between the US and Iran and threats to shipping by the Iran-backed Houthi militia in Yemen.

Brent crude futures were up $2.23, or 2.45%, at $93.24 a barrel by 1323 GMT, after hitting a session high of $95.47.

US West Texas Intermediate crude climbed $2.18, or 2.18%, to $86.18.

Both benchmarks touched their highest levels since June 11.

The Brent crude three-month timespread, meanwhile, expanded to $10.89 a barrel, its widest since May 22, deepening backwardation on mounting supply risks. Backwardation is where prompt crude trades above later-dated barrels, typically signalling tighter near-term supply.

The US military said it carried out an 11th consecutive night of attacks on Iran. The US attacks came a short while after the Kuwaiti army said its air defences were intercepting Iranian drones.

President Donald Trump said on Wednesday the US would "bomb and destroy one bridge or power plant" any time Tehran targets a ship in the Strait of Hormuz.

As well as the renewed conflict over control of that key waterway, the Iran-aligned Houthis have opened a new front in the war by threatening to target vessels carrying Saudi oil in the Bab el-Mandeb strait and announced a naval blockade of Saudi Arabia.

Ships with links to Israel, the United States or Saudi Arabia are at a higher risk of being attacked by Yemen's Iran-aligned Houthi militia and are advised to avoid voyages through the Red Sea and Gulf of Aden, the European Union's naval force Aspides said on Wednesday.

"The energy market now has the dual-strait worry, with the Bab el-Mandeb Strait looking like it could join the Strait of Hormuz as a hot spot, as traders closely watch shipping numbers in the Red Sea," said Tim Waterer, chief market analyst at KCM Trade.

Bab el-Mandeb at the southern entrance to the Red Sea has become an increasingly important route for Saudi Arabian crude exports as traffic through the Strait of Hormuz has fallen sharply again since a ceasefire between the United States and Iran collapsed earlier this month.

Three oil tankers loaded with Saudi crude for China and India made U-turns in the Red Sea on Tuesday, heading towards the Suez Canal rather than braving the Yemeni coast.

Four other tankers also changed course in the Red Sea on Wednesday.

"The (Houthi) threat has led tankers to divert which could further pressure the physical market and Saudi exports, contributing to push prices to the upside," said Frank Walbaum, market analyst at trading platform Naga.com.  

In response to the Houthi warnings, Asian refiners are seeking to ship crude oil from Saudi Arabia's Red Sea port of Yanbu through the Suez Canal and around Africa.