Republican US presidential nominee Donald Trump speaks as Democratic US presidential nominee Hillary Clinton listens during their third and final 2016 presidential campaign debate at UNLV in Las Vegas, Nevada, US, October 19, 2016. [Photo/Agencies]

PUTIN'S PUPPET?

Trump, 70, and Clinton, 68, battled sharply over the influence of Vladimir Putin on Wednesday, with Clinton calling Trump the Russian president's puppet and Trump charging Putin had repeatedly outsmarted Clinton.

Clinton said Trump had refused to condemn Putin and Russia for recent cyber attacks.

"He'd rather believe Vladimir Putin than the military and civilian intelligence officials that are sworn to protect us," Clinton said.

US intelligence agencies and the Department of Homeland Security have said the Russian leadership was responsible for recent cyber attacks on the Democratic National Committee and the leaking of stolen emails.

Trump rejected the idea that he was close with Putin, but suggested he would have a better relationship with Russia's leader than Clinton.

"He said nice things about me," Trump said. "He has no respect for her, he has no respect for our president and I'll tell you what, we're in very serious trouble."

Clinton responded: "Well that's because he'd rather have a puppet as president of the United States."

"No, you're the puppet," Trump retorted. "Putin has outsmarted her and Obama every single step of the way," he said in a reference to US President Barack Obama, a Democrat like Clinton.

Clinton also said Trump had been "cavalier" about nuclear weapons and should not be trusted with the nuclear codes.