Casablanca, Morocco (CNN) -- A moderate Islamist party claimed victory in Morocco's first parliamentary elections since constitutional reforms this summer.
The Justice and Development Party (PJD) won 107 of the 395 seats, Interior Minister Taib Cherkaoui said Sunday.
The next biggest winner was the Istiqlal Party, also known as the Independence Party, with 60 seats, the Interior Ministry's website reported.
The number of parties involved in Morocco's multiparty system means it was unlikely a single party would win a majority of the seats, so a coalition government would have to be formed.
U.S. Secretary of State Hillary Clinton offered her congratulations Saturday "on the successful completion" of the elections.
"The United States stands ready to work with the new parliament and the people of Morocco to strengthen the rule of law, raise human rights standards, promote transparent and accountable governance, and work toward sustained, democratic reform," she said.
Turnout in the North African country was 45%, the Interior Ministry said Friday.
The National Democratic Institute -- which had 41 accredited observers from 21 countries that went to over 200 polling stations on Friday -- said in a news release that the elections "were conducted transparently." The voting process was described as "technically sound" and "without fear of tampering or procedural violations."
But one institute member, Canadian Liberal Party leader Bob Rae, also pointed to the turnout and a number of invalid and spoiled ballots as negatives.
"Seeing the number of people who actively spoiled their ballots as well as those who did not participate, it is clear that the path to real change will take more effort and time," Rae said.
Lise Storm, senior lecturer in Middle East Politics at the University of Exeter in England, said Friday that the outcome might signal whether the population is happy with the monarchy or not.
The more votes for the PJD appear to indicate a desire for greater change, she said -- as opposed to votes for the bloc of traditional loyalist parties, which would suggest voters favor the status quo.
Under the new constitution, approved by referendum in July, both Parliament and the prime minister have greater powers, while the monarch's sway has been slightly lessened.
The changes mean the prime minister must now be chosen from the party that wins the greatest number of votes -- which, based on the preliminary results, would be the Justice and Development Party -- rather than King Mohammed VI selecting his own nominee for the job.
The reforms came after thousands of Moroccans took to the streets to demonstrate earlier this year, inspired by what became known as the Arab Spring.
The youth-based February 20 Movement called for jobs and an end to corruption its members say stems from royal cronies.
Analysts say economic reform is needed to create more jobs for the country's young people, particularly many university graduates who are unemployed.
Journalist Aida Alami contributed to this report.