Oil edged back toward US$137 a barrel Thursday in Asia amid lingering concerns over Iran's nuclear conflict and reports of lower-than-expected US oil stockpiles. "The bull run is really not over yet. The Iranian nuclear situation remains fluid and the market faces supply-side risks with global demand outpacing supply," said Victor Shum, an oil analyst with Purvin & Gertz in Singapore. "It remains likely that pricing will gain strength and rise to a new peak in the coming weeks," he said. Midday in Singapore, light, sweet crude for August delivery was up 37 cents at US$136.42 in electronic trading on the New York Mercantile Exchange. The contract seesawed Wednesday in the floor session before settling a penny higher at US$136.05, ending two days of sharp declines that left prices 6.4 percent below last week's record high.