Weakness in miners drags on Britain's FTSE

* FTSE 100 drops 0.2 percent

* Anglo leads miners lower as industrial unrest resurfaces

* Index holds above 6,300, indicating underlying strength

By Alistair Smout

LONDON, Feb 18 (Reuters) - Britain's top share index fell on Monday, with the mining sector hit by low commodity prices and a resurgence in industrial unrest.

However, the index remained above the key support level of 6,300, keeping it around five-year highs.

The mining sector was the main drag on the FTSE 100, losing 0.9 percent after copper fell to a three-week low. Volatile copper miner Kazakhmys was a top faller on the index, losing 2.8 percent.

Miners specialising in gold fared little better, with the commodity having hit a 6 month low last session. Fresnillo lost 0.7 percent in Monday's session.

"Base metal prices are not at the high levels we expected for the start of 2013, and that's hit miners. We don't see that much high demand from the euro zone, U.S. and Asia," Myrto Sokou, senior research analyst at Sucden Financial Private Clients, said.

Anglo American saw losses and volume pick up in afternoon trade after a clash at Anglo's Amplats platinum mine in a labour dispute.

Anglo American shed 2.8 percent, among the top FTSE fallers. On Friday, it had managed gains despite poor earnings, as investors had hoped it had put a torrid 2012 - in which production was marred by industrial disputes - behind it.

Miners had rallied since November on hopes of renewed demand from China as growth picked up after a period of political transition at the end of last year.

"Miners have done very well as a China play, and there's an element of unwind to that. I'm pretty cautious on Chinese infrastructure plays, so I think there's more weakness in the miners to come," Robert Quinn, chief european equity strategist at Standard & Poor's Capital IQ, said.

At the close, the FTSE 100 was down by 10.07 points, or 0.2 percent lower, at 6,318.19 points, with the materials sector - which includes commodity-related stocks such as miners - taking 6.6 points off the index.

The session was a quiet one, with the U.S. equity market closed for the Presidents' Day holiday. Only half of the average 90-day volume was traded across the index as a whole.

Lawmakers in the United States are on holiday this week, leaving four days for members of Congress to negotiate a deal to avoid automatic budget cuts due to kick in at the beginning of March, which could crimp demand in the world's biggest economy, and impact company earnings.

However, despite the session's falls, the FTSE did not test support at the 6,300 level, indicating that there was still good underlying strength in the index.

After the best January since 1989, the FTSE has traded sideways this month, dipping below 6,300 for over a week in early February. The index has held up above that level since it passed it again last Tuesday.

"The recent rally has faded, and we've seen a consolidation, although the FTSE has stayed fairly strong," Sokou said.

"It's good that we're back above 6,300 and have held that." (Editing by Alison Williams)