WELLINGTON (Reuters) - New Zealand said on Monday it will extend the deployment of troops training Iraqi defense forces in their fight against Islamic State militants.

The troops, which currently number around 105, would remain in Iraq until November 2018, 18 months longer than previously planned, Defence Minister Gerry Brownlee said in a statement.

"This is having a tangible effect on the Iraqi army's ability to take and hold ground from Daesh," said Brownlee, referring to Islamic State.

"It makes sense to continue doing something that adds value to the likelihood of Iraqi peace and security in the future, and to amend our mission to meet the changing environment in Iraq."

The New Zealand Defence Force works with around 300 Australian troops providing training on basic weapons skills as well as medical support and logistics. The mission has trained around 7,000 members of the Iraqi security force since it began in 2015, according to the New Zealand government.

The government had also authorized troops to train other Iraqi forces such as the police, who were tasked with securing cities once they had been freed from Islamic State, the defense minister said.

(Reporting by Charlotte Greenfield; Editing by Nick Macfie)