The United Kingdom's foreign secretary is urging Parliament to withhold aid to nations in which Christians are persecuted.

"I think we should do more for the estimated 240 million Christians who face persecution for their faith around the world," Jeremy Hunt told members of parliament.

The U.K.'s foreign aid budget in 2017 was about $18 billion.

Hunt, responding to questions from lawmakers, said an ongoing review will ensure the U.K. is pressuring nations in which Christians are persecuted.

"Where the U.K. makes large aid payments, such as in Afghanistan," he said, "it is absolutely essential that we make it clear to the government in those countries that we are expecting progress on freedom of religious belief."

The review, led by Philip Mounstephen, the bishop of Truro, monitors persecution of Christians in the Middle East, Asia and Africa.

The review will assess how much support the U.K. currently provides and recommend how government ministers should respond.

Hunt cited the worldwide Christian group Open Doors' estimate that more than 4,300 Christians were killed because of their faith over the last year.

The U.K.'s Christian Institute said the real figure probably is much higher, as friends and relatives of victims often are afraid to report incidents.

In the meeting with lawmakers, Hunt was asked about Open Doors' prediction of a 14 percent increase in persecution of Christians this year.

Hunt said Open Doors has documented four out of five people worldwide who suffer persecution for their faith are Christians.

"The most striking statement [in the Open Doors report] is that the vast majority are in the very poorest countries: this is not, on the whole, a problem affecting people who live in affluent countries," Hunt told lawmakers.

North Korea is among the worst offenders, he said.

The review, he said, "is to ensure that we use all the U.K.'s diplomatic leverage to highlight these issues and put pressure on those regimes to change."

Hunt said the U.K. has considerable influence, because of its aid, in high-persecution states such as Afghanistan, Libya, Sudan and Somalia.

Hunt said that in the past, "there has been some hesitation" in the nation's advocacy for persecuted Christians.

"Now is the time when we have to put all that behind us and say that freedom of religious belief is an essential and indivisible part of freedom, full stop. The U.K. should always be on the right side of that issue."