By Julia Harte

WASHINGTON (Reuters) - The Organization for Security and Cooperation in Europe said on Wednesday that human rights were respected during Tuesday's U.S. presidential election and there were few cases of intimidation, despite recent changes to election rules in several states that created unnecessary burdens for voters.

"Some legal and administrative decisions appear to have had a partisan flavor," Ambassador Audrey Glover, head of the OSCE election observation mission to the United States, said at a news conference on Wednesday. "These recent changes ... led to a lack of clarity regarding the rules."

Tuesday's astonishing contest, in which Republican candidate Donald Trump beat his long-favored opponent, Hillary Clinton, to become the 45th president of the United States, was the first election to occur in the United States in more than 50 years without the full protections of the landmark Voting Rights Act.

The U.S. Supreme Court in 2013 struck down a provision of the law that had allowed federal oversight of states with a history of racial discrimination, prompting the U.S. federal government to reduce its own election monitoring program.

The OSCE deployed nearly 300 observers to polling stations in 33 states, although they were not allowed to freely observe early voting and Election Day in 19 of those states, according to the international rights group.

At almost half of the polling sites observed by the OSCE delegation, some citizens who wanted to vote were not found on the voter list, causing "systemic concern regarding the effectiveness of voter registration methods," according to the group.

Despite concerns that voters would be intimidated at the polls, the OSCE said, its observers did not see any serious incidents. However, U.S. civil rights groups logged unusual levels of voter intimidation complaints, receiving about 35,000 calls through a national voter complaint hotline as of Tuesday evening.

Revised voting laws and lengthy court battles in many states also left voters uncertain about when and where they could cast their ballot and whether they would need to present photo identification.

(Reporting by Julia Harte; Editing by Jonathan Oatis)