UPDATE 1-Poland's TPSA seeks advisor for web portal sale-sources
* TPSA sent out memos inviting potential advisors -sources
* Analysts value internet arm at $159-190 mln (Adds further details, analyst's comment, share price)
WARSAW Jan 8 (Reuters) - Poland's top telecoms group TPSA is seeking an advisor for a possible sale of its internet portal, two sources told Reuters, as it struggles with competition from other mobile operators and an economic slowdown.
The former monopoly, a unit of France Telecom, has seen revenue fall steadily because of its shrinking fixed line business and regulator-driven cuts in mobile rates, combined with intensifying competition.
TPSA told Reuters last month it may unload or seek a partner for Wirtualna Polska, one of the country's most popular web portals, after warning of lower 2012 earnings.
Analysts value Wirtualna at 500-600 million zlotys ($159-$190 million) and said local media group Agora was a likely buyer.
One source said that TPSA had sent a memo to potential advisors to the sale of Wirtualna, while a second confirmed the company is seeking an advisor on the sale.
TPSA and Agora declined to comment.
In September, a joint venture of Germany's Axel Springer and Swiss Ringier won approval to buy Poland's top web portal Onet from broadcaster TVN for 956 million zlotys.
"Wirtualna seems the next best thing after TVN successfully sold Onet," said a Warsaw-based analyst. "Onet went to Ringier Axel Springer for 13 times EBITDA (earnings before interest, taxes, depreciation and amortisation). Ten times or slightly lower is more probable with Wirtualna."
TPSA, which also slashed its dividend payout plans in the October profit warning, had said it was facing increasingly aggressive competition in a shrinking market.
"TPSA is looking for all possible ways to unfreeze cash, facing a bad situation on the market, possible investments into new frequencies. And Wirtualna is most definitely a non-core asset," said Leszek Iwaszko, analyst at Societe Generale.
TPSA shares slipped 0.9 percent by 1448 GMT, slightly underperforming the market. ($1 = 3.1497 Polish zlotys) (Reporting by Adrian Krajewski and Agnieszka Barteczko; Editing by Louise Heavens)