The White House on Wednesday congratulated Malaysia's prime minister on his coalition's election victory but urged the government to address concerns about election irregularities.
"We note concerns regarding reported irregularities in the conduct of the election, and believe it is important that Malaysian authorities address concerns that have been raised," White House spokesman Jay Carney said in a statement. "We look forward to the outcome of their investigations."
Prime Minister Najib Razak's Barisan Nasional coalition extended its 56-year rule but recorded its worst-ever election performance in Sunday's election. His party won 133 seats in Malaysia's 222-member parliament, seven fewer than in 2008 and short of the two-thirds majority it had hoped for.
Opposition leader Anwar Ibrahim's People's Alliance won 89 seats, a big increase from seven in 2008. Anwar has said the result was tainted by electoral fraud and scheduled a large rally in Kuala Lumpur to press for electoral reforms.
The Malaysian government rejected charges of electoral fraud and has accused Anwar of seeking to cause unrest with the rally.
The election was one of the most closely contested in Malaysia in years and Najib is expected to face a party leadership challenge that may cost him his leadership by the end of the year because of the weak showing.
He had hoped to strengthen the ruling coalition's majority in parliament with the help of a strong economy, reforms to roll back race-based policies and $2.6 billion in spending programs benefiting poor families.
Najib is now seeing as having a difficult time in persuading his allies to press ahead with economic reforms and the phasing out of policies favoring ethnic Malays over other groups.