MANILA (Reuters) - President Rodrigo Duterte ordered the cancellation on Monday of Philippine's purchase of police rifles from the United States, after U.S. senatorial aides said last month that Washington was halting the sale due to concerns about human rights violations.

"We will not insist on buying expensive arms from the United States. We can always get them somewhere else. I am ordering the police to cancel it. We don't need them," Duterte said in a televised speech at a event attended by Muslim rebel leaders.

"We will just have to look for another source that is cheaper and maybe as durable and as good as those made in the place we are ordering them," Duterte said.

In Washington, U.S. State Department spokesman Mark Toner told reporters it was his understanding "we (the United States) have not received any notification ... on the cancellation."

The relationship between the United States and the Philippines, a long-time ally, has been complicated lately by Duterte's angry reaction to criticism from Washington of his violent battle to rid the country of illegal drugs.

More than 2,300 people have been killed in police operations or by suspected vigilantes as part of government's anti-narcotics efforts, which was the linchpin of his election campaign.

Last month, Senate aides told Reuters that the U.S. State Department halted the planned sale of some 26,000 assault rifles to the Philippines' national police after Senator Ben Cardin said he would oppose it because of concerns about human rights violations.

Duterte has said in the past that Russia and China had shown willingness to sell arms to the Philippines.

(Reporting by Karen Lema; Additional reporting by Arshad Mohammed in Washington; editing by Simon Cameron-Moore and Grant McCool)