* Her imprisonment threatens EU-Ukraine trade pact
* Yanukovich fears ex-PM could stage comeback
* Breakthrough in parliament unlikely
KIEV, Nov 21 (Reuters) - Ukraine's parliament met on Thursday to try to pass a law that would allow jailed opposition leader Yulia Tymoshenko to go to Germany for medical treatment, clearing the way for a landmark trade deal with the European Union.
However, President Viktor Yanukovich has taken a harder line in negotiations with the EU this week and a breakthrough on Tymoshenko, his fiercest opponent, looked unlikely in the session.
The free trade and cooperation agreement is due to be signed at a summit on Nov. 29 and would mark a strategic shift westwards for the former Soviet republic away from Russia.
But ex-prime minister Tymoshenko's plight has become symbolic of what the EU sees as a problem of selective justice in Ukraine and has become the key to success at the meeting in the Lithuanian capital of Vilnius.
"Tomorrow (Nov 21) there will be nothing emerging. There is no draft text (on Tymoshenko)," Yanukovich's representative in parliament, Yury Miroshnichenko, told Fifth Channel television station on Wednesday night.
The 52-year-old is serving a seven-year sentence for abuse of power following a trial which Western governments say was political. She has been in a prison hospital because of back trouble and Germany has offered her treatment in Berlin.
Tymoshenko was only narrowly defeated by Yanukovich in a run-off vote in February 2010. He is the key figure in any deal in parliament but was on a visit to Austria on Thursday.
Yanukovich, who fears Tymoshenko's political rehabilitation could harm his chances of re-election in 2015, has stalled over letting her go and his allies, who dominate in parliament, have so far blocked agreement on the law that would allow her to go abroad.
Tymoshenko came to international prominence as the braided-haired co-leader of the 2004-5 Orange Revolution protests. She was convicted in 2011 for abuse of office in brokering a gas deal with Russia which the Kiev government says saddled the country with an exorbitant price for gas.
Many EU governments see her as a high-profile victim of Ukraine's justice system and would like to see her released before the summit.
Anxious to prise Ukraine away from Russia's historic embrace, the EU has focused on a compromise by having Ukraine adopt a law under which Tymoshenko would be allowed to go to Germany for medical treatment.
Tymoshenko's supporters expressed frustration at the repeated delays in making progress on the law.
"Leaders of the three opposition parties have repeatedly stated their readiness to unequivocally support any proposal relating to the fate of Yulia Tymoshenko," a statement from Tymoshenko's Batkyvshchyna (Fatherland) party said on Wednesday.
"But not a single one of the five draft laws (for Tymoshenko's release) are acceptable to Yanukovich and the (ruling) Regions Party," the statement said.
Earlier in the week Yanukovich took a sudden tough line in EU negotiations, telling the EU's point-man on Ukraine, commissioner Stefan Fuele, that in the current situation he could not sign in Vilnius, a European diplomatic source said.
Yanukovich, who has wrong-footed Russia - Ukraine's big supplier of gas - by sticking to his pro-EU course, was likely to be bluffing to secure better financial terms from the 28-member bloc, the source said.
(Additional reporting by Pavel Polityuk and Natalya Zinets; Writing By Richard Balmforth; editing by Anna Willard)