The Palestinian government on Saturday condemned as "terrorism" the killings of three young Palestinian-Americans in North Carolina and called on U.S. authorities to include its investigators in the probe.

Police have charged a neighbour with Tuesday's shooting in the town of Chapel Hill of Deah Barakat, 23, his wife Yusor Abu-Salha, 21, and her sister Razan Abu-Salha, 19, saying the incident followed a dispute over parking.

But investigators said they were also looking into whether the suspect, Craig Stephen Hicks, was motivated by hatred toward the victims because they were Muslim.

Branding Hicks "an American extremist and hateful racist", the Palestinian Foreign Ministry said the incident suggested a rise in dangerous discrimination against American Muslims.

"We consider it a serious indication of the growth of racism and religious extremism which is a direct threat to the lives of hundreds of thousands of American citizens who follow the Islamic faith," the ministry said in a statement.

It called for "a serious investigation and the involvement of Palestinian investigators to clarify the circumstances of these assassinations and premeditated murders" in Chapel Hill.

On Thursday, Turkish President Tayyip Erdogan criticised U.S. President Barack Obama for "staying silent" over the murders, which have garnered international attention and left some American Muslims feeling concerned about their safety.

"This has hate crime written all over it," said the slain women's father, Mohammad Abu-Salha.

On Friday, Obama issued a statement describing the incident as "brutal and outrageous" and said no one in the United States should be targeted for their religion.