UPDATE 1-Agora increases layoffs to a total of 400 staff

(Adds background)

WARSAW May 13 (Reuters) - Polish media group Agora AGOD.WA is increasing staff cuts to 400 from 300, the company said in a statement on Wednesday.

Agora said it would dismiss the workers - some 10 percent of staff - by the end of October and would set aside a reserve of 2.3 million zlotys to cover layoff costs which would affect first half-year results.

The publisher of Poland's largest non-tabloid - Gazeta Wyborcza - has been hit by falling circulation and dwindling advertising revenues.

Analysts expect it to post a first quarter net loss of around 0.4 million zlotys when it reports results on may 14. (Writing by Dagmara Leszkowicz; Editing by David Cowell)