The pound fell against other currencies following the release of weaker-than-expected UK economic data.
Official figures showed industrial output fell by 0.7% in February from the month before, while construction output shrank by 1.7%.
Separate data showed the UK's deficit in goods and services widened to ¬£3.7bn in February, from ¬£3bn in January.
The pound fell 0.4% against the dollar to $1.2418 and dropped 0.3% against the euro to 1.1686 euros.
Elsewhere, markets remained wary following news of the US missile attack on a Syrian government airbase.
Worries over disruption to oil supplies in the Middle East sent the price of crude surging. The price of Brent oil rose 2% to stand above $56 a barrel at one point, before slipping back to $55.26.
Gold - traditionally seen as a haven asset in times of uncertainty - rose 1.25% to $1,253.75 an ounce.
The rise in the gold price lifted shares in Randgold Resources. Its shares were the biggest risers in the FTSE 100, climbing 2.6% .
Overall, London's benchmark share index was up 13.43 points at 7,315.04 shortly after midday.
Shares in Sainsbury's rose 2% while Tesco was 1.5% higher after UBS assigned a "buy" rating to both of the supermarkets.
However, in the FTSE 250, shares in Ocado fell 4.7% after UBS cut its rating on the online grocer to "sell" from "buy".