* Opposition fears president set to sign Moscow pact
* Hopes for a million participants in Sunday rally
* Police want to eject protesters from key buildings (Recasts with arrival of more protesters, fresh quotes)
By Gareth Jones and Richard Balmforth
KIEV, Dec 8 (Reuters) - Pro-Europe protesters flocked to Kiev's Independence Square on Sunday for a rally that organisers were hoping would swell to 1 million people, piling pressure on Ukrainian President Viktor Yanukovich to turn back from seeking closer ties to Russia.
The rally, due to start at 12 p.m. (1000 GMT), will increase the tensions in a standoff between the government and protesters furious over its decision to dump a landmark pact with the European Union in favour of a trade deal with Moscow.
In a gesture likely to infuriate Yanukovich, protesters hoisted a huge portrait of his jailed arch foe Yulia Tymoshenko onto a towering New Year Tree, festooned with anti-government placards, that overlooks the tent 'village' on the square.
Protesters have been infuriated by speculation that Yanukovich, who met Russian President Vladimir Putin in Sochi on Friday, may take Ukraine into a Moscow-led customs union, a move the opposition says fits Putin's design of recreating the Soviet Union.
"The whole country is suffering because of this government," said student Sasha Trojan, 20, who had taken an early train to Kiev from the city of Poltava, about 300 km (200 miles) away.
"If Yanukovich stays in power, we will end up like Belarus," she said, citing opposition fears that Yanukovich, shored up with Russian money, will clamp down on dissent just as President Alexander Lukashenko has done in neighbouring Belarus.
"We want a European Ukraine," said Vasil Didukh, 23, who like many of the protesters had come from western Ukraine, the powerbase of Tymoshenko and other opposition leaders.
The protests, the largest Ukraine has seen since the 2004-05 Orange Revolution, have raised fears for political and economic stability in the ex-Soviet state of 46 million people, which borders four EU nations and is the main transit route for Russian gas to Europe.
Around 350,000 people joined a similar rally last Sunday, one day after riot police beat protesters and journalists in a crackdown that drew condemnation from Western governments.
"BREAKUP OF COUNTRY"
Police have since threatened to eject protesters occupying public buildings including Kiev's City Hall, which is a stone's throw from the makeshift barricades limiting access to the nucleus of the protest movement on Independence Square.
"Our protest is peaceful but we will bring pressure to bear on this government so that our demands are met," Vitaly Klitschko, one of the three main opposition leaders and a world heavyweight boxing champion, said on Saturday.
The square has been transformed into a makeshift village of tents, festooned with Ukrainian blue and yellow flags, EU flags and opposition banners, beneath a large television screen. People huddle around braziers for respite from the winter cold.
Speculation that Yanukovich may be poised to sign up to Moscow's customs union, thus slamming the door on joining a free trade pact with the EU as originally envisaged, galvanised the protest.
Moscow and Kiev have both sought to play down such talk, saying the customs union was not even discussed in Sochi, but they confirmed the two governments would meet on Dec. 17.
"Any signature to a deal on forming a new Soviet Union means the breakup of the country," said Arseny Yatsenyuk, a former economy minister, now prominent in the opposition, who leads the Tymoshenko faction in parliament.
Tymoshenko was jailed in 2011 for seven years for abuse of office linked to a gas deal with Russia. The EU says she is the victim of a political vendetta and tried to secure her release before the talks with Yanukovich on a trade pact collapsed.
Yanukovich and Putin, who regards Ukraine as strategically vital to Moscow's own interests, are widely believed to have struck a bargain whereby Ukraine obtains cheaper Russian gas and possibly credits in exchange for backing away from the EU.
Ukraine sorely needs external help to meet looming gas bills and debt repayments, but such arguments hold little sway with the protesters, who say their demands are about more than money.
"Our hearts demand a revolution," said Dennis Cherniavsky, 25, who works for an agricultural firm. "This is no longer about joining the EU, it is about having a humane government." (Additional reporting by Alissa de Carbonnel; Writing by Gareth Jones; Editing by Richard Balmforth and Kevin Liffey)