** U.S. oil and gas companies decline in pre-market trading; crude prices extend decline on escalating trade tensions

** Brent futures LCOc1 down 3% at $63.57/bbl while U.S. West Texas Intermediate crude CLc1 falls 3.2% at $60.03/bbl by 0806 GMT O/R

** Oil plunged 7% on Friday as China retaliated against U.S. President Donald Trump's tariffs, escalating a trade war and increasing fears of a slowdown in global economy and weakening oil demand

** U.S. oil majors Exxon Mobil XOM.N and Chevron CVX.N lose 4.8% and 3.66%, respectively

** Last week, XOM slumped 11.37%, CVX tanked 13.73%

** Oil and gas producers ConocoPhillips COP.N down 4.1%, while EQT Corp EQT.N, Occidental Petroleum OXY.N and Devon Energy DVN.N drop between 4.55% and 5%

** Top oilfield services firm SLB SLB.N declines 3%, Halliburton HAL.N falls 4.85%

** Europe's index of oil companies .SXEP plummets 6.38%

(Reporting by Arunima Kumar in Bengaluru)

((Arunima.Kumar@thomsonreuters.com; Twitter: https://twitter.com/Aru_Kumar94 ;))