Oil prices fell almost 6% to two-week lows on Monday as optimism grew that the United States and Iran were moving closer to a peace deal that would reopen the Strait of Hormuz, even though Washington and Tehran played down hopes for an imminent breakthrough.

Brent crude futures were down $6.12, or 5.9%, at $97.42 a barrel at 1643 GMT and US WTI futures were down $5.72, or 5.9%, at $90.88. Both contracts traded at their lowest since May 7. Iran’s top negotiator and its foreign minister were in Doha for talks with Qatar’s prime minister on a potential deal with the US to end the three-month-old war, an official briefed on the visit said Monday.