The Supreme Rada adopted the law December 21 allowing parliamentary factions to nominate candidates for prime minister, defense minister and foreign minister if the president failed to make relevant nominations by constitutional deadlines.
Arseniy Yatsenyuk, deputy head of the presidential secretariat, said the law "violates 11 constitutional norms."
"The principle of divided authority in Ukraine has been distorted to form a very serious source of influence in the executive branch," he said, adding that the law interfered with the work of the president and the judicial system.
From January 1, 2006, Ukraine shifted from a presidential-parliamentary to a parliamentary-presidential form of governance, which saw some presidential powers transferred to the parliament and the government.
President Viktor Yushchenko and his supporters said the law on the Cabinet, which makes the government the supreme executive body, effectively enabled ministers led by Prime Minister Viktor Yanukovych, who received Russia's backing in the presidential race against Yushchenko in 2004, to usurp power.
Western-leaning Yushchenko, who came to power on the back of the "orange revolution" following the presidential elections, refused Thursday to sign into law the bill on the Cabinet and returned it to the Supreme Rada for reconsideration along with a number of proposals.
The parliament managed Friday to override Yushchenko's veto with 366 votes, rejecting each of his 42 amendments.
Yushchenko said the law lacked a mechanism to ensure his presidential authority during the nomination of a prime minister, and failed to outline the process of dismissing ministers appointed by the president.
Members of the pro-presidential bloc Our Ukraine walked out of parliament Friday in protest against the law.
The prime minister, for his part, said the law would help resolve numerous issues facing Ukraine.
"We are not going to use our authority to address any personal questions," Yanukovych said. "We will use our authority to resolve the problems our country is wrestling with."
Yanukovych's appointment in August was designed to put an end to four months of political wrangling following parliamentary elections in March.
