Russia's president has called for European leaders to end their criticism over Ukraine's decision to delay an EU pact, as thousands rallied in Kiev in a third day of protests.

Vladimir Putin said on Tuesday a free trade deal between the European Union and Ukraine that was controversially put on hold last week would have been a "major threat" to the Russian economy.

Also on Tuesday, Kiev admitted Moscow had asked it to delay signing the pact, while President EU Yanukovych said he would consider signing under new terms.

The Ukrainian government suspended talks last week on the political and free trade accord, seen as a key step towards EU membership, which its Soviet-era master Russia had vehemently opposed.

The shock decision sparked the largest protests to hit the ex-Soviet country since the pro-democracy Orange Revolution in 2004, with demonstrators taking to the streets in the capital Kiev and western Ukraine.

Imprisoned opposition leader Yulia Tymoshenko, whose freedom was one of the EU demands rejected by Kiev, announced on Monday that she was on hunger strike until the EU deal was signed.

The EU has accused Russia of pressuring its smaller neighbour not to sign the deal at a summit in Vilnius this week.

'Better terms' wanted

EU President Herman Van Rompuy and European Commission head Jose Manuel Barroso have said they "strongly disapprove" of Russia's actions, prompting Putin to urge European leaders to tone down their criticism.

"I ask our friends in Brussels, my personal good friends in the European Commission, to hold back on the sharp words," Putin said during a visit to Italy.

"Do we have to choke entire sectors of our economy for them to like us?"

President Yanukovych has called for calm after at times violent mass demonstrations that have seen riot police fire tear gas at protesters who hurled traffic cones and rocks at security forces.

On Tuesday he said the government wanted better terms for the EU deal.

"As soon as we reach a level that is comfortable for us, when it meets our interests, when we agree on normal terms, then we will be talking about signing," Yanukovych said in a televised interview.