* FTSE 100 down 0.6 pct, mid caps down 0.4 pct
* G4S drops after Q2 revenue disappoints
* North Korea tensions rattle equity markets
* Safe haven precious metals miners in demand (Adds detail, updates prices at close)
LONDON, Aug 9 (Reuters) - Britain's top share index was shaken from its summer lull on Wednesday as geopolitical tensions hit equity markets globally, sending investors into safe-havens such as gold mining stocks, while an earnings update weighed on shares in G4S.
Britain's blue chip FTSE 100 index ended the session down 0.6 percent at 7,498.06, broadly in line with a negative European market.
Shares in precious metals miners Fresnillo and Randgold Resources topped the index, gaining nearly 5 percent and 2.8 percent respectively, as investors fled to safe-haven assets on worries over tensions between the United States and North Korea, with Pyongyang saying it was considering plans for a missile strike on Guam.
"Equity markets have behaved as you would expect by selling off sharply, an entirely predictable outcome at any time but more so when volatility levels are as low as they are now," Michael Hewson, chief market analyst at CMC Markets UK, said.
Elsewhere, disappointing second-quarter revenue growth hit shares in security services firm G4S, which sank 7.5 percent and marked their worst day since March 2016. The shares had gained around 40 percent this year ahead of the earnings release.
"Interim EPS is in line with expectations but organic revenue growth slowed considerably in Q2, mainly due to emerging markets, and comparables are tougher in H2," analysts at Jefferies said in a note.
"In addition, working capital disappointed and the pension deficit increased."
Among sectors, financials were the biggest weight, taking around 18 points off the index, while health care stocks and miners also added pressure.
There were some dramatic moves among mid-caps stocks, with beleaguered gold miner Acacia Mining also lifted 7.7 percent by a rush to safe-havens.
While the rise helped Acacia Mining's shares touch a two-week peak, its shares have slumped more than 46 percent so far this year on the back of an export ban in Tanzania and changes to the country's mining industry.
Shares in Ladbrokes Coral helped bring up the rear, dropping more than 5 percent as top shareholders sold their shares in the betting firm, while Essentra dropped 5.4 percent after broker Numis cut its rating on the stock to "hold" from "add." (Reporting by Kit Rees; Editing by Angus MacSwan and Alister Doyle)