Police are carrying out a major search for a man armed with a shotgun and a knife who stabbed an elderly woman to death at a retirement home for Catholic missionaries in southern France.

Prosecutors said a suspect with no apparent link to Islamic terrorism had been identified after the incident in the village of Montferrier-sur-Lez, near Montpellier.

City prosecutor Christophe Barret said the suspect is believed to be someone "in the entourage of this retirement home".

He said investigators had discovered an airgun and other items in a car near the residence that helped identify the suspect.

About 100 police officers are searching for the suspect following the attack.

Mr Barret earlier told reporters that a woman who works at the retirement home called police on Thursday night to say she had been attacked.

When officers arrived, they found the body of another woman, gagged and tied up outside the building with three stab wounds.

The worker who alerted police did not suffer serious injuries but was deeply shocked, and no-one else at the residence was harmed, the prosecutor said.

Security forces searched the complex but did not find the killer. Around 60 people live who live at the facility are not in danger, and the search is continuing in a larger perimeter with help from a helicopter and police dogs.

The residence, called Green Oaks, is operated by the African Missions Society, and takes in retired priests, nuns and others who have worked in Africa.

Olivier Ribadeau Dumas, spokesman for the French Catholic bishops' conference, tweeted condolences for the woman killed and added: "Our prayers reach out also to the missionaries attacked in their retirement home in the Herault (region). God give them all peace."