London: Sex worker and law graduate Laura Lee is due to appear before Northern Ireland's High Court on Monday to challenge a law making it illegal to pay for sex.

Northern Ireland criminalised the purchase of sex in 2015 - the first part of the United Kingdom to pass such a law - in a move some advocacy groups said would help stamp out sex trafficking.

Sex worker and rights activist Laura Lee in Belfast, Northern Ireland, last year. Credit:Getty Images

Other groups have criticised the law, saying it will drive the sex trade underground and increase the risk of violence women face.

"I'm challenging this bill because it creates an extremely dangerous environment for sex workers," Lee said.