By Oksana Kobzeva and Zlata Garasyuta

MOSCOW (Reuters) - Goldman Sachs <GS.N> has laid off staff in Russia in recent months and more cuts are expected by the end of the summer after the U.S. firm posted weak first-quarter results, sources said.

The cuts to headcount come as global investment banks have retreated from Russia because of an economic slowdown and Western sanctions over the Ukraine conflict.

Takeovers, stock market listings and international sales of stocks and bonds have slumped due to the sanctions.

One of the sources said on Wednesday Goldman had laid off traders, back office staff and investment bankers in Russia recently and linked the cuts to the bank posting its worst quarterly results in more than four years in April.

A source at Goldman said the bank was cutting more than 10 percent of its staff in Russia and the bulk of the cuts would be in the investment banking division due to a lack of deals.

Both sources said there would be more reductions in the firm's headcount in Russia by the end of the summer.

A Goldman representative said the job cuts were in line with cuts it has made across the firm globally.

(Additional reporting and writing by Alexander Winning; Editing by Adrian Croft and Alexander Smith)