Tunisian Foreign Minister Mongi Hamdi has been appointed to head the UN peace mission in Mali, where 31 peacekeepers have been killed in attacks since it deployed 18 months ago.

Hamdi, 55, replaces Dutch diplomat Albert Koenders who led the 9,300-strong MINUSMA force since last year, the UN announced on Friday.

Hamdi had been foreign minister since January and has held various positions within the UN system over the past 25 years.

His appointment comes as the United Nations is looking to strengthen its peacekeeping mission in Mali following a string of brazen attacks in the north of the country, where Islamist groups are seeking to regain a foothold.

Northern Mali was occupied by Islamist groups in April 2012, who imposed a brutal rule before being driven out by French troops nine months later.