UK's FTSE on track for worst fall since January as Pru drops

* FTSE 100 down 1.6 pct, slips further from record highs

* Prudential CEO Thiam leaves for Credit Suisse (NYSE: CS - news)

* Tullow, BG renew oil price-linked slide

* Possible sale of securities arm lifts Charles Stanley (LSE: CAY.L - news)

By Sudip Kar-Gupta

LONDON, March 10 (Reuters) - Britain's top share index was headed for its worst drop since mid-January on Tuesday following a sharp fall in insurer Prudential (SES: K6S.SI - news) prompted by the departure of its chief executive officer for Credit Suisse .

The market was also hit by losses in energy stocks such as Tullow Oil (LSE: TLW.L - news) and BG as oversupply and weak demand combined to push Brent crude oil futures down.

The blue-chip FTSE 100 index shed 1.6 percent to 6,762.56 points towards the close of the trading session, retreating further from a record high of 6,974.26 points set on March 2.

The index was on track for its second worst one-day fall so far this year after a 2.4 percent decline in mid-January.

Prudential fell 2 percent as the departure of its chief executive Tidjane Thiam for Credit Suisse took the shine off a 14 percent rise in 2014 operating profits.

"Thiam's departure is disappointing for the Pru (HKSE: 2378-OL.HK - news) ," said Admiral Markets' Darren Sinden.

The weak oil price sent Tullow Oil down 7.5 percent while BG fell 6.4 percent.

Engineer Weir Group fell 3.3 percent, reversing some recent gains. It had rallied nearly 12 percent since last Thursday on speculation that Weir, hurt by cutbacks in investment by oil firms, might attract interest from U.S. private equity.

On a brighter note, security group G4S (LSE: GFS.L - news) edged up 0.5 percent after posting a bigger-than-expected rise in 2014 profits.

Shares (Berlin: DI6.BE - news) in financial services group Charles Stanley, which is not in the main FTSE 100 index, rose 5.4 percent after the company said it might sell off its Charles Stanley Securities division.

Some investors have said uncertainty ahead of a British general election in May could hinder the FTSE in the near-term and prevent it from hitting record highs in the 7,000 point region.

Gerren O'Neill, senior trader at Thames Capital Markets, said the FTSE could drift lower in the coming weeks but find support in the 6,700 or 6,600 point level.

"We continue to see further downside from here, but any pullback should be relatively short-lived," he said. (Additional reporting by Alistair Smout; Editing by Gareth Jones)