Oil prices were on track on Tuesday for their biggest quarterly decline since the early months of the Covid-19 pandemic in 2020, as investors closely monitored the possibility of fresh US-Iran talks amid growing uncertainty over a fragile ceasefire agreement.Brent crude futures for August delivery, which expire on Tuesday, rose 12 cents, or 0.16%, to $73.27 a barrel by 0959 GMT. Despite the gains, the contract was headed for a third consecutive monthly decline and had fallen about 20% so far in June. The more actively traded September Brent contract gained 32 cents, or 0.43%, to $74.23 a barrel.US West Texas Intermediate (WTI) crude for August delivery rose 27 cents, or 0.38%, to $71.02 a barrel. However, the benchmark remained on course for a second straight monthly loss, down around 19% in June, Reuters reported.Both Brent and WTI prices have now returned close to their pre-war levels. Markets remained focused on the possibility of renewed diplomacy between Washington and Tehran. While US President Donald Trump said Iran had requested talks and a meeting could take place in Doha, Iranian officials denied that any negotiations had been scheduled.Iranian deputy foreign minister Kazem Gharibabadi said on Monday that Iranian and Omani experts would soon begin discussions on redefining transit routes through the Strait of Hormuz, adding that Tehran would seek to restrict vessels operating outside designated shipping lanes.However, Iran’s foreign ministry spokesperson Esmaeil Baghaei dismissed reports of imminent talks with Washington, saying there would be “no negotiation meetings at any level with the American side in the coming days.”The uncertainty surrounding possible negotiations has highlighted the fragility of the June 17 agreement aimed at halting hostilities, restoring shipping through the Strait of Hormuz and stabilising global energy markets. The conflict has also emerged as a political challenge for Trump ahead of November’s congressional elections. Meanwhile, investment bank Morgan Stanley lowered its forecast for Dated Brent crude prices in 2027 by $5 per barrel, projecting prices at $75 per barrel in the first half of the year and $70 per barrel in the second half, citing expectations of rising commercial oil inventories among OECD countries. The bank also forecast an implied global oil market surplus of 4.8 million barrels per day in 2027.