France will respond to Algeria's "unjustified" decision to expel 15 French officials, Foreign Minister Jean-Noel Barrot said on Monday, as relations between the countries worsened further.

France's ties with its former colony have long been complicated, but took a turn for the worse last year when President Emmanuel Macron angered Algeria by backing Morocco's position over the disputed Western Sahara region.

There had been a short-lived thaw in tensions last month after Barrot visited Algiers, but a week later tit for tat diplomatic expulsions once again strained ties.

Algeria's press agency APS reported on Monday that France's charge d'affaires had been informed that 15 French diplomatic agents were in irregular positions and would be expelled.

"The departure of agents on temporary missions is unjustified and as I did last month, we will respond immediately and in a strong and proportionate manner," Barrot told reporters in Normandy.

France in mid-April recalled its ambassador to Algiers for consultations and expelled 12 agents serving in the Algerian consular and diplomatic network in France after Algiers had expelled 12 French diplomatic staff.

A poor relationship has major security, economic and social repercussions. Trade is extensive and around 10% of France's 68 million population has links to Algeria, according to French officials.

"This is a decision that I regret because it is not in the interests of Algeria, nor in the interests of France," Barrot said, declining to give further details on the response from Paris.