US President-elect Donald Trump awards key roles to top Republican party official and conservative media chief

US President-elect Donald Trump has selected Washington insider Reince Priebus as White House chief of staff and firebrand outsider Stephen Bannon as senior counselor.

Less than a week after his unexpected victory over Democrat Hillary Clinton in last Tuesday's presidential election, Trump's choice on Sunday of Priebus, the Republican National Committee chairman and friend of House of Representatives Speaker Paul Ryan, could help him repair his strained relations with members of the Republican Party establishment.

White House chief of staff is considered one of the most powerful positions in Washington, charged with helping the president in almost every task and operating the complicated machinery of government.

According to Reuters news agency, Priebus embodies the Republican establishment in Washington and will play a critical role in shepherding Trump's agenda in Congress. But Trump also named Bannon, the combative former head of the right-wing website Breitbart News, as his strategist and senior counselor.

Trump’s statement named Bannon first, despite the vague title of his role.

The statement said Bannon and Priebus would be "working as equal partners to transform the federal government."

"I am thrilled to have my very successful team continue with me in leading our country," Trump said. "Steve and Reince are highly qualified leaders who worked well together on our campaign and led us to a historic victory. Now I will have them both with me in the White House as we work to make America great again."

Trump added that Bannon and Priebus were both "highly qualified leaders" who helped him win the White House race.

Bannon mentioned his “very successful partnership” with Priebus, who said in his own statement that the Trump White House would “work to create an economy that works for everyone, secure our borders, repeal and replace Obamacare and destroy radical Islamic terrorism”.