March 14 - Britain's top shares gained slightly early on Monday as disruption to nuclear power after a massive earthquake in Japan boosted energy firms, but Burberry slid on fears that demand there for luxury goods would slump.

Burberry Exotics Collection - 2011

By 0932 GMT, the FTSE 100 was up 5.18 points or 0.1 percent at 5,833.85.

The earthquake in Japan had a mixed impact on UK equities, with fashion group Burberry topping the list of fallers, shedding 5.4 percent as investors worried about the impact on demand for high-end products.

UK-listed insurers were also hit by the quake as sentiment on the sector was damaged, although they have no exposure to losses in Japan. Standard Life fell 1.9 percent while Resolution slipped 1.5 percent.

However temporary power supplier Aggreko topped the list of gainers up 5.3 percent while energy firm BG Group gained as it was seen benefiting from extra demand after Japan's nuclear energy supply was severely damaged in the earthquake.

Both these stocks saw extremely heavy volumes traded.

"Disruptions to nuclear power supply could see Japanese (liquid natural gas) demand increase. This would reduce global LNG oversupply, and support a recovery in European gas & power prices," UBS said in a note.

Xstrata and mid-cap Drax Group which supply coal, also benefited as the demand outlook for non-nuclear energy sources perked up.

Other miners were also a significant source of support for the index with Rio Tinto up 2 percent after it edged closer to gaining control of coal producer Riversdale Mining after a $3.9 billion sweetened bid rallied more shareholders to accept the offer.

The fact that turmoil in the Middle East has not spread further despite continuing violence in Libya is also helping prevent sharper falls, investors said.