The EU called for calm in Ukraine Monday and urged authorities to show restraint after a weekend of violent clashes between police and thousands of pro-democracy protesters furious at Kiev's rejection of an EU pact. Separately, President Viktor Yanukovych telephoned European Commission head Jose Manuel Barroso to ask that Brussels receive a Ukraine delegation to discuss "some aspects" of the pact and an associated free trade deal. Barroso said the delegation was welcome and the Commission was ready to "discuss aspects of implementation related to the agreements already initialed but not to re-open any kind of negotiations." President Yanukovych accepted these terms, a Commission statement said, with the timing to be decided later. The Commission also said Yanukovych "explicitly confirmed the intention to investigate the use of force by the police" during the conversation with Barroso. Yanukovych had agreed also that all sides should show restraint, all civil rights and liberties should be respected, and that the government engage with "relevant political forces." A "peaceful and political solution is the only way for Ukraine out of the current situation," the Commission said. Earlier, Maja Kocijancic, a spokeswoman for EU foreign affairs chief Catherine Ashton, said "we encourage all parts of Ukrainian society to resolve their differences peacefully." "Protests need to take place in a peaceful atmosphere," she said, adding that "Ukrainian authorities need to show restraint. "We have condemned the violence... we have also expressed our support for freedom of speech and assembly." Protesters on Monday declared a general strike and thousands blockaded government buildings in Kiev. Nearly 10,000 had camped out overnight Sunday in central Kiev in a bid to keep alive Ukraine's biggest pro-democracy protest since the 2004 Orange Revolution. That followed a weekend of violent clashes over Ukraine's rejection of a pact with the EU that would have seen it edge closer to membership of the bloc and break away from former master Russia. Security forces fired dozens of stun grenades and smoke bombs at masked demonstrators who were pelting police with stones and Molotov cocktails. Kiev's city government said in an update Monday that 165 police officers and demonstrators had been wounded in the most serious clashes witnessed in Ukraine since the Soviet Union's demise.