LONDON (Reuters) - Britain's top shares index climbed to its highest closing level in 11 months on Wednesday, boosted by a rise in insurance stocks, although a slump in Anglo American (>> Anglo American plc) pushed down the mining sector.

The blue-chip FTSE 100 index <.FTSE> ended up 0.5 percent at 6,728.99 points -- its best closing level since August 2015.

Insurance company Admiral (>> Admiral Group plc) rose 2.8 percent after UBS upgraded the stock to "buy" from "neutral", helping to lift shares in rival Legal & General (>> Legal & General Group Plc) by 3.1 percent.

Healthcare stocks Shire (>> Shire PLC) and Hikma (>> Hikma Pharmaceuticals Plc) also gained ground.

Traders said the healthcare sector remained in favour for its "defensive" characteristics of solid profits and dividends, given general uncertainty over Britain's vote last month to quit the European Union.

While the FTSE 100 has managed to recover from an initial slump after the Brexit vote, the hit to sterling has dented the value of the FTSE 100 in U.S. dollar terms for international investors.

"The health sector has been a traditional, defensive play. There is an element of nervousness creeping into the market currently regarding what the implications of the Brexit will be, so pharmaceuticals do present some form of a safe haven in terms of volatility," said Jonathan Roy, advisory investment manager at Charles Hanover Investments.

Mining stocks underperformed, with Anglo American (>> Anglo American plc) falling 4.8 percent after reporting a setback in its iron ore production.

The FTSE 350 Mining index <.FTNMX1770> dropped 2.4 percent, marking its fourth straight session of losses.

"There is a good chance the earnings downgrade cycle may be over for the resources sector, with commodity prices regaining strength and demand fundamentals looking slightly better," said Russ Mould, investment director at AJ Bell.

(Editing by Catherine Evans)

By Kit Rees