Oil prices rose for the fifth straight trading day on Thursday, topping $98 a barrel, driven by intensified Houthi attacks on tankers in the Red Sea and growing worries about Middle East supplies.

According to OilPrice.com, September Brent futures were up nearly 5% at $98.73 a barrel at the time of writing, having earlier touched $98.91.

US benchmark WTI climbed above $90 a barrel, rising 4.4% after reports that the Houthis appear to have begun carrying out threats to strike Saudi oil exports in the Red Sea and Bab el?Mandeb area.

The chokepoint in the Red Sea is critical for Saudi shipments: in recent months, the kingdom rerouted more than 70% of exports that previously transited the Persian Gulf to the Red Sea port of Yanbu.

Incidents in the area reportedly forced at least two tankers to turn back before reaching the Bab el?Mandeb. Sources said one vessel was carrying Saudi oil to India and the other to China.

Yemeni Houthi sources claimed strikes on two Saudi tankers in the narrow passage, citing violations of the maritime blockade they declared. "We struck two Saudi oil tankers, Encelia and Layla, for violating the blockade decision issued by the armed forces," Houthi spokesman Yahya Sarea said, quoted by Al Jazeera.

These incidents heighten risks to shipping and regional oil supplies, a trend reflected in global price movements.