Asked about the release of political prisoners by China, Trump told reporters on board Air Force One: "I did bring him up, it's a tougher one for him, it's a tougher one."

Trump added: "He said, he told me, Jimmy Lai is a tough one for him to do."

Lai, the 78-year-old founder of the now-defunct Apple Daily newspaper, was found guilty in December on charges of foreign collusion and seditious publication and sentenced to 20 years in prison.

The sentence was the harshest penalty doled out so far under a national security law imposed on Hong Kong by Beijing after widespread pro-democracy protests in 2019 and received international condemnation.

Trump added Friday that Xi promised "He's going to strongly consider the pastor," referring to Jin Mingri, the founder of a prominent Chinese underground church detained in October in a sweeping national crackdown.

Jin founded the unregistered Zion Church in 2007 in Beijing. It grew to 1,500 members before shuttering in 2018 under pressure from Chinese authorities.

But the church maintained an online presence that flourished during the Covid-19 pandemic, amassing a following across 40 Chinese cities.

Jin was arrested on October 10 on "suspicion of the illegal use of information networks."