LONDON—Oil prices extended gains on Tuesday from a near 5 percent rebound the day before as concerns about the impact of the Omicron coronavirus variant on global fuel demand eased and Iran nuclear talks stalled, delaying the return of Iranian crude. Brent crude futures were up $1.66, or 2.3 percent, at $74.74 a barrel by 1005 GMT, after settling 4.6 percent higher on Monday. U.S. West Texas Intermediate crude was at $71.30 a barrel, up $1.81, or 2.6 percent, building on a 4.9 percent gain in the previous session. Oil prices were pummelled last week by concerns that vaccines might be less effective against Omicron, sparking fears that governments may re-impose restrictions to curb its spread and hit global growth and oil demand. However, a South African health official reported over the weekend that Omicron cases there had only shown mild symptoms. Also, the top U.S. infectious disease official, Anthony …