The FTSE 100 edged higher in early morning trading, up 0.31% or 15.80 points to 5,148.74.
BP led gains following weekend reports the Obama administration told ExxonMobil it would not prevent a takeover bid for its troubled British rival. BP's shares rose 5.29% to 384.1p.
Early morning gainers also included Cobham, up 2.14% to 233.4p, while Intertek Group advanced 0.96% to £15.85.
Meanwhile, Man Group was the biggest faller, down 1% to 217.5p. Other losers include Inmarsat, dropping 0.75% to 729.5p, while Sage Group dipped 0.72% to 232.9p.
On Wall Street, the Dow Jones index was up 0.58% or 59.04 points to 10,198.03 ahead of US earnings season this week.
Companies reporting second quarter earnings over the next five days include Alcoa, JPMorgan Chase and Bank of America.
In Japan, the Nikkei added 0.39% or 37.21 points to 9,548.11 despite the Government losing its majority in the upper house in yesterday's elections. Investors had expected the ruling party to lose.
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