An interim petition calling for religious freedom in North Korea has notched up more than 20,000 signatures from concerned Christians in the UK.

Persecution watchdog Release International presented the petition to the North Korean embassy in London last week.

It demands that the oppressive communist country grant freedom of worship to Christians, who faith regular harrassment by the authorities and can be arrested or imprisoned for even owning a Bible.

Recent reports by human rights organisations accuse North Korea of putting up to 180,000 people into forced labour.

There are reports that Christians are among the inmates facing torture, starvation and execution in political prison camps.

Release International is working to support North Korean Christians who have fled their country by providing safe houses, pastoral support and health care.

"Those who've got away describe these camps as 'hell on Earth'," said Release International.

"In this land where a form of emperor worship is practised, Christians can be detained, brutally tortured and removed from society.

"Some risk being shot by border guards as they try to flee the country to avoid persecution and oppression."

Release International is still collecting signatures and will present the final petition to the North Korean embassy at the end of its campaign.

It appealed to more Christians to sign the petition.

"20,000 people have already stood with persecuted North Koreans by signing the petition calling for freedom. It's not too late to take your stand," it said.

The petition can be signed online at www.releaseinternational.org/petition