Prime Minister Scott Morrison has spoken to United States President Donald Trump about the outlook for a major trade deal between the US and China amid predictions of an agreement before the end of the year.

Mr Morrison phoned Mr Trump on Monday morning, Canberra time, to thank the President for America's help in freeing an Australian man held hostage by the Taliban in Afghanistan.

The conversation also ranged across relations with China but there was no confirmation of whether the two leaders spoke about revelations of Chinese interference in Australia and the potential defection of a Chinese spy.

Australian government sources said the two leaders had a "very positive" call set up by Mr Morrison to thank Mr Trump for the efforts to free Timothy Weeks, an Australian academic taken hostage three years ago.