BT hit weighs on hedge fund Lansdowne's January returns - letter

* Developed Markets Fund down 2.9 pct in January

* Takes 1.3 pct hit from slide in BT's share price

* Comcast (Swiss: CMCSA.SW - news) , Amazon, Facebook (NasdaqGS: FB - news) all help to offset losses

By Maiya Keidan

LONDON, Feb 17 (Reuters) - After ending last year down heavily, the value of London-based Lansdowne Partners' main fund slid again in January after shares in crisis-hit BT Group (Other OTC: BTGOF - news) plunged, a letter to investors seen by Reuters showed.

Lansdowne, one of Britain's oldest hedge funds, struggled last year, losing 15 percent in its main vehicle, the $9.3 billion Developed Markets Fund, according to a report by HSBC. The same fund fell a further 2.9 percent in January, the letter showed.

The biggest drag in the opening weeks of the year was BT, which lost the fund 1.3 percent when it shed a fifth of its value on Jan. 24 after it made deeper provisions for an accounting scandal in Italy and warned on profit.

The continued poor performance comes after a tough period for many hedge funds, which prompted Lansdowne Chairman Stuart Roden to tell the industry it needed to stop making excuses for poor performance.

Among other holdings to weigh on January's performance was British satellite telecoms company Inmarsat (Other OTC: IMASF - news) , which cost the fund 0.9 percent.

Helping offset some of those losses, the firm made gains from a number of 'long' positions, a bet the share price will rise, in firms including Comcast Corp, Amazon.com (NasdaqGS: AMZN - news) and Facebook Inc, the letter showed.

Other winnng investments included International Consolidated Airlines and Booker Group Plc (LSE: BOK.L - news) .

A spokesman for Lansdowne declined to comment. (Reporting by Maiya Keidan; Editing by Keith Weir)