* Revenues seen rising by 3 pct in euro terms this year-CEO
* Operating profit margin seen at 14-15 pct of revenues-CEO
* Board considering 1-10 stock split to boost liquidity
* Shares down 0.9 pct, slightly underperforming market (Adds detail, more comments, market reaction)
BUDAPEST, Feb 7 Hungarian drugmaker Richter flagged a further fall in profitability for 2013 on Thursday due to rising sales costs and higher research and development spending on new products.
Richter earlier reported a 53 percent rise in fourth-quarter net profit, recovering from a loss its financial operations posted a year earlier and benefiting from declines in administrative and other operating costs.
But for the full year, Richter's operating profit margin fell to 15.4 percent of revenues from 19.8 percent a year ago due to the cost of expanding its sales network in Western Europe, as well as rising research and development spending.
Richter, which makes gynaecological, cardiovascular and central nervous system drugs, said its revenues could rise by 3 percent this year from 1.13 billion euros in 2012, but operating profit margin could sink further to 14-15 percent.
At 0937 GMT, its shares were 0.9 percent lower at 37,010 forints on the Budapest Stock Exchange, slightly underperforming the blue chip index, which was 0.2 percent lower.
Chief Executive Erik Bogsch told a news conference Richter expected sales and marketing spending to inch up to about 29 percent of revenues in 2013 from 28.4 percent last year, while research and development spending is estimated at 12-13 percent, a notch above 11.9 percent in 2012.
He said Richter received a milestone payment worth about $15 million in the first quarter after its U.S. partner Forest Laboratories Inc. submitted a new drug application to the U.S. Food and Drug Administration (FDA) for anti-psychotic drug Cariprazine.
"In a favourable case this procedure can conclude by the end of the year and in a favourable case the drug could hit the market in 2014," Bogsch said, adding the company may receive another milestone payment after FDA approval.
He said bargaining government price subsidies for Esmya, a medicine to treat uterine fibroids, took longer than expected but the company still expected revenue from this product to rise more than four-fold to 15 million euros this year.
Bogsch said the company would not change its dividend policy, which targets a payout of 25 percent of net profit to shareholders.
However he added that Richter's board was considering a 1 to 10 stock split to boost the liquidity of shares, an idea that has already come up several times in the past.
"The main goal is to boost liquidity," Bogsch said. "The board is now leaning towards this, but a full assessment is still under way." (Reporting by Gergely Szakacs; Editing by Erica Billingham and Mark Potter)