KIEV, Ukraine — Thousands of protesters demanded changes to the constitution Thursday in a march to the Ukrainian parliament, but President Viktor Yanukovych gave no indication he would offer them more concessions.
The protesters, many of them wearing masks and camouflage, peacefully marched past a large deployment of police guarding parliament and other government buildings.
The opposition said about 20,000 people participated while pro-government media put the number at 3,000.
Inside parliament, opposition leader Arseniy Yatsenyuk said constitutional amendments were necessary to end the "dictatorial powers" enjoyed by Yanukovych.
Yatsenyuk announced that his Fatherland Party would submit a bill to change the constitution at the next session on Tuesday.
Both Yatsenyuk and rival opposition leader Vitaly Klitschko have refused an offer from Yanukovych to become prime minister and deputy prime minister, respectively, saying they want changes to the constitution that give the opposition a say in Cabinet posts.
Ukraine has been mired in a political crisis since mass anti-government protests broke out in November after Yanukovych suddenly suspended a planned trade agreement with the European Union and sought closer ties with Russia instead.
After the rallies turned violent last month, Yanukovych dismissed the government, revoked anti-protest laws and signed an amnesty law.
However, in a decree published late Wednesday, Yanukovych indicated he would not appoint a new government soon as he expanded the powers of acting Prime Minister Serhiy Arbuzov and his Cabinet.
Also on Thursday, an opposition activist was seriously hurt when a parcel bomb exploded inside the protesters' headquarters in central Kiev.
The Interior Ministry said the 15-year-old was taken to hospital but that police could not investigate because protesters refused to let officers into the Trade Union Building, where the explosion occurred.
Meanwhile, the European Parliament called on the EU to impose sanctions on those responsible for attacks on protesters in Ukraine.
A resolution passed in Strasbourg, France, said travel bans and asset freezes should be slapped on "Ukrainian officials, legislators and oligarchs personally responsible for the attacks on and deaths of protesters."
Lawmakers also called for the EU to offer short- and long-term financial support to Ukraine.
The Ukrainain Foreign Ministry called the resolution disappointing and biased. "Calls for sanctions do not help to create national reconciliation but destroy the stabilization process," the ministry said in a statement.
EU foreign ministers are scheduled Monday to discuss the situation in Ukraine. They have not raised the prospect of sanctions yet, and German Foreign Minister Frank-Walter Steinmeier said Wednesday that it was too early for that.
In a separate resolution, the European Parliament criticized Russia for putting pressure on its neighbors, arguing that "Ukrainian citizens alone have the right to decide the future of their country."
Moscow has vehemently rejected such criticism and accused the EU and the United States of openly pressuring Ukraine.
Russian President Vladimir Putin is planning to hold talks with Yanukovych on the sidelines of the Sochi Olympics, Kremlin spokesman Dmitry Peskov said Thursday.