Oil services stocks were the best performers in London on Tuesday, helped by a confident outlook by sector giant Petrofac. Oil producers were also making decent gains as escalating tensions in the Middle East continued to push crude prices higher - Brent futures were trading at a six-month high today.Petrofac's share price surged on Tuesday as the oilfield services group reiterated its guidance for the full year despite reporting a decline in revenues and profits in the first half. It still anticipates to deliver "modest growth" in net profit this year.The firm said it had made a "good start to the year" operationally and that the bid pipeline opportunities for the future remain strong. Markets were also pleased by comments about the Mexico where it is seeing increased investment in oil and gas projects as the nation opens up its energy industry.Revenue totalled $2.79bn in the six months ended June 30th, down from $3.19bn the year before, reflecting the scheduling of recent contract awards and the rephasing of the In Salah southern field developments in Algeria which was hit by a terrorist attack in January. Net profit fell from $326m to $243m. Both figures however were better than analysts' estimates.Oil prices jumped today after US Secretary of State John Kerry said last night that Syria would be held accountable for the "moral obscenity" of an alleged chemical weapons attack that has killed well over a thousand people. "By any standard it is inexcusable," he said, sparking speculation of a potential US involvement in the Syrian crisis.Brent for October delivery was up 2.3% at $113.33 a barrel on the InterContinental Exchange after hitting $113.60, its highest in half a year.US Defense Secretary Chuck Hagel said that the US has "assets in place" and forces are "ready to go" if intervention is decided. Meanwhile, UK Prime Minister David Cameron recalled parliament to vote on possible response to last week's attack.Syrian Foreign Minister Walid al-Muallem responded by saying that the government - which has not yet claimed responsibility - wouldn't step down and its defences would "surprise" those wanting to step in.Shell, BP, Premier Oil, BG Group and a host of others in London were registering moderate gains this afternoon as oil prices rose.Top performing sectors so far todayOil Equipment, Services & Distribution 23,865.66 +1.64%Oil & Gas Producers 7,801.04 +1.02%Industrial Transportation 3,108.32 +0.78%Electricity 9,997.53 +0.47%Pharmaceuticals & Biotechnology 11,389.77 +0.23%Bottom performing sectors so far todayAutomobiles & Parts 7,820.83 -3.35%Construction & Materials 3,806.79 -2.72%Forestry & Paper 11,137.58 -2.27%Technology Hardware & Equipment 1,038.96 -2.20%Financial Services 6,854.00 -2.18%BC