LONDON: Oil prices rose on Monday, remaining at their highest since mid-October as colder weather spurred buying while further support was provided by a weaker US dollar and expectations of tighter sanctions on Iranian and Russian oil exports. Brent crude futures gained 49 cents, or 0.6 percent, to $77 a barrel by 4:19 p.m. Saudi time, their highest since Oct. 14. US West Texas Intermediate crude was up 49 cents, or 0.7 percent, at $74.45, its highest since Oct. 11.