Blue chips stock edged higher after heavyweight oil and gold stocks lifted following the US military's missile attack on a Syrian government airbase.
Brent Crude hit its highest level for a month, rising 1% to $56 a barrel in early trading after US ships in the Mediterranean launched a barrage of Tomahawk missiles on the Shayrat air base in central Syria, part of Bashar Assad's regime.
The FTSE 100 Index lifted 10.6 points to 7313.8, as oil majors rose once news of the attack was announced.
BP was 2.5p higher at 467p, while Royal Dutch Shell was up 21.3p to 2229p.
Gold, an asset class traders buy in troubled times, lifted 1.3% at $1,253.75 an ounce. This saw African gold miner Randgold Resources as the strongest performer in the top flight rising almost 3%, or 195p to 7300p. Mexican gold and silver miner Fresnillo lifted 27p to 1621p.
Spreadex financial analyst Connor Campbell said because of the number of large oil and mining stocks based in London "the FTSE was the only major European index to edge into the green".
The biggest afternoon risers in the FTSE 100 Index were Randgold Resources (+195p to 7300p), Mediclinic International (+16.5p to 700p), Standard Life (+6.7p to 362.5p), British Land Company (+11.5p to 647.5p) and Sainsbury's (+4.5p to 259p).
The biggest afternoon fallers in the FTSE 100 Index were Rio Tinto (-59.5p to 3198p), Anglo American (-18.5p to 1226.5p), Glencore (-4.3p to 315.1p), ITV (-2.8p to 214p) and BT Group (-4p to 310.3p).
The biggest afternoon risers in the FTSE 250 Index were Cairn Energy (+7.8p to 211p), Hunting (+16.5p to 604.5p), Aberdeen Asset Management (+7.4p to 274.7p), McCarthy & Stone (+4.8p to 189.1p) and Indivior (+8.1p to324.3p).
The biggest afternoon fallers in the FTSE 250 Index Ocado Group (-14.4p to 237.6p), Evraz (-7p to 231.7p), Redefine International (-1p to 36.8p), Vedanta Resources (-16p to 812p) and CLS Holdings (-36p to 1895p).