UPDATE 2-Polish TVN expects more pain from TV advertising market

* Q2 loss 231 million zlotys, vs 213 mln loss forecast

* Sees 2012 TV ad market down 6-9 pct, after 7.5 pct H1 fall

* Shares drop further 6 pct after 18 pct decline this year (Releads on forecast; adds share reaction, analyst quote)

By Agnieszka Barteczko and Adrian Krajewski

WARSAW, Aug 9 (Reuters) - Polish broadcaster TVN warned of more gloom in the local television advertising market on Thursday, predicting that spending will shrink by as much as 9 percent this year due to an uncertain economic outlook.

The company, which has been shedding assets to reduce debt, reported a larger-than-expected net loss in the second quarter, saying the advertising market shrank 7.5 percent in the first six months of the year.

"Following its worse than expected evolution in the second quarter, no improvement in July-August and continued low visibility going forward, our outlook for the full year TV advertising market dynamics is a decline in the range of 6-9 percent," Chief Executive Markus Tellenback said in a statement.

"We believe that TVN advertising revenue should develop broadly in line with the market," he said.

TVN shares, which had shed 18 percent this year, dropped another 6 percent in morning trade, making them the worst performers in Warsaw's main WIG20 index.

"(The advertising market forecast) is significantly below what could have been expected," Societe Generale analyst Leszek Iwaszko said. "This is very negative news, implying a big drop in the second half of the year."

TVN, which produces Polish versions of foreign formats such as "Kitchen Nightmares" as well as its own original output, took a 350 million zlotys ($106.2 million) charge in the second quarter on the sale of its Internet arm, which dragged it to a net loss of 231 million zlotys, worse than the 213 million predicted by analysts.

It earned 68 million zlotys in the same period of last year.

With a net debt of 2.74 billion zlotys, or 4.8 times its core profit (EBITDA), TVN agreed to sell Poland's top Internet portal Onet to a joint venture of German publisher Axel Springer and Swiss group Ringier for less than its book value.

It is also awaiting permission from authorities to sell its pay-TV arm to Vivendi's Canal+ to focus on its core broadcast operations.

TVN said it would seek to buy back some of its debt. ($1 = 3.2954 Polish zlotys) (Edited by Chris Borowski and Robin Pomeroy)