Ukraine is often described as a divided country, but the scene in central Kiev this weekend provides an unusually striking picture of the split.

From western Ukraine, anti-government protesters crammed into cars, hitchhiked or took one of the hundreds of free buses laid on to take them from their home towns to Independence Square in Kiev over the past few days.

At the same time, from the east and south of the country, others arrived at Kiev's central station on Saturday morning in special trains arranged by the government to bring their own supporters from their heartlands to the capital, and show that not all of Ukraine supports the protests that have gripped the country in the weeks since the government pulled out of signing an association agreement with the EU.

With just 100m between them, two rival rallies began on Saturday lunchtime, and are due to last all weekend, in an uneasy standoff that many fear could lead to clashes.

Ukraine's ethno-linguistic divide. Photograph: Observer

The pro-government rally is set up, somewhat ironically, on European Square, while huge barricades of snow, iron railings and car tyres fence off the main protest tent camp of Independence Square. Divided by the barricade and a line of police buses, the two very different Ukraines face off, competing stages booming out music and speeches.

In the neutral zone between the rallies, groups of pro-Europe supporters edged towards the police buses, waving placards and singing the national anthem over the heads of the riot police, while a sextet of Cossacks in medieval dress patrolled on horses.

"You are slaves!" shouted a group of anti-government protesters across the police lines.

An angry man in a black leather jacket shouted back: "We are working hard, while you are lazing around on the square protesting! Go back to work!"

So far the protest movement has seen hundreds of thousands of people on the streets of Kiev, the city's statue of Lenin toppled, and an ill-judged storming of the barricades around Independence Square by riot police. After prolonged struggles, the police eventually withdrew, leaving the protesters free to rebuild the barricades twice as high and reassert their occupation of the very centre of Kiev.

The core of the anti-government protest movement has come from western Ukraine, a region where Ukrainian nationalism is rife and people consider themselves already part of Europe. Unlike eastern Ukraine, the western area was not brought under Soviet control until the second world war, and distrust of Russia remains strong.

At a popular restaurant in Lviv, the biggest city in the west, a heavily armed man dressed in anti-communist resistance fatigues greets arriving diners with the words "Glory to Ukraine!" and demands to know whether there are any Moskali, a derogatory term for Russians, among the group. If Moskali are detected, a mock execution is carried out on the spot, gunshots ringing out as other diners tuck into their borscht and sausages.

The restaurant may be gimmicky, but the anti-Russian sentiment is real. In addition to the aspirational EU flags decking everything from the town hall to a statue of Neptune, there are also handwritten posters dotted around town proclaiming, possibly somewhat prematurely: "Russia Goodbye!"

Souvenir shops sell mugs and fridge magnets with the slogan "Thank you God that I was not born a Moskal."

Dozens of buses leave Lviv each day, ferrying anyone who wants to protest the 300 miles to Kiev for free. Organisers estimated that more than 2,000 people a day are using the buses, with many more making their own way to the capital by car or train. In recent days, the number has increased as people come to protest for the weekend.

In Rava-Ruska, a town of 10,000 people just two miles from Ukraine's border with Poland, mayor Irina Vereshchuk responded with fury to the decision by president Viktor Yanukovych not to sign the EU pact and dictated a letter to be dispatched to Brussels. Writing that the Ukrainian government had signed up to an agreement with "the former Evil Empire, the Soviet Union", Vereshchuk requested that the EU sign an association agreement with Rava-Ruska, whether or not the rest of the country was with her.

"We have been preparing for this for years, and then suddenly it was cancelled," she said in Rava-Ruska's town last week. "There was no war, or tsunami. Nothing unexpected happened. So why didn't we sign it?"

In the west of Ukraine, the authorities openly support the protest. Andriy Sadovyy, the mayor of Lviv, says that after the first day of clashes in Kiev, he summoned the regional heads of law enforcement and the interior ministry, and they assured him that "what happened in Kiev could never happen in Lviv", and the police would never attack protesters.

This weekend, Vereshchuk and other mayors from small towns in western Ukraine have travelled to Kiev, to stand on Independence Square and be with the protesters. Vereshchuk tells how, before she set off, hundreds of residents descended on her office with supplies of homemade food and warm clothes for her to take to the capital and distribute among the protesters.

The catastrophic situation in the Ukrainian economy can be felt acutely in Rava-Ruska. Vereshchuk says the average salary is less than £150 a month, and she has not been able to pay government employees for four months, as the money has "all been stolen". She refuses to accept Yanukovych's reasoning that the EU pact could not be signed because of the ill effects it would have on the economy. Russia promised Ukraine financial woe if it signed the deal, as well as dangling carrots of loans, trade concessions and cheaper gas prices if the country stayed away from Brussels.

"We don't want Putin's money," says Vereshchuk. "This is a civilisational choice. Europe doesn't give cash; it gives us a chance. All you need to do is cross the border to see the difference in living standards. Fifteen years ago, Poles were coming here to buy vodka. Now look how far they've come."

The atmosphere at the pro-government rally in Kiev on Saturday was muted. Most people did not want to speak, and many of those who did were ambivalent about the rally and were not even listening to the speeches from the stage. Some admitted that they had been forced to come to Kiev for the weekend under threat of losing their job.

"I can't say I like those people on the Maidan [Independence Square] much," said one man carrying a flag bearing the logo of Yanukovych's party, who refused to give his name. "I am for European integration, eventually and without hysteria. But I don't trust any politicians. I don't like the opposition leaders. But the president is an idiot as well, of course."

During the Orange Revolution and the 2010 presidential election, Yanukovych was able to mobilise hundreds of thousands of genuine supporters from the east, but that fervour has cooled. Even in the cities of the east, there is discontent with the deteriorating economic situation for most of the country, as members of the president's family become richer.

Many Ukrainians are still suspicious of the EU and of the nationalist west, but there are few fervent defenders of Yanukovych and his policies.

"Ukraine is no longer split between east and west; it is split between those who are apathetic and those who care," says Otar Dovzhenko, 32, one of the organisers of the protest in Lviv. "There are just more apathetic people in the east. But even there, there is almost nobody who is ready to go out into the street and really support better relations with Russia."

Western Ukrainians view their eastern brethren as blinkered and scared. "The western part of Ukraine has always had a European mentality," says Sadovyy, the mayor of Lviv. "Over the past few hundred years we have been part of six different empires, while the eastern part of the country has only been part of one. Our city was given the Magdeburg Rights [German civil law] 657 years ago; this is the kind of experience that eastern Ukraine just doesn't have."

Vereshchuk likens the east to an elephant in a zoo, tied by a very thin piece of rope. "People who visit the zoo look at the elephant and wonder why it stands in the same place – with just a couple of shakes of its head it could break the rope and go free. But the elephant has been tied since childhood and remembers that, before, the rope was strong and it could not escape, and now it does not even try to break free."

For their part, the eastern Ukrainians see the west as naive and lazy, out on the streets protesting while the workers of the east toil hard in coal mines and metal plants to keep the economy going.

"You're protesting. We're working," read a common sign at the pro-government rally.

As evening falls in Kiev, the two rallies continue to coexist more or less peacefully. But even if the truce is kept, and whatever Yanukovych does in the coming weeks, the long-term task of uniting the very different parts of this country is likely to vex Ukrainian leaders for many years to come.