Reality TV star Kim Kardashian returned to New York "badly shaken" on Monday after being robbed at gunpoint in her Paris residence by masked men who robbed her of €5 million ($13 million) worth of jewellery. 

Kardashian, wearing sunglasses and with her head bowed, was pictured entering her Manhattan apartment with her rapper husband, Kanye West. She had left Paris by private jet hours after robbers tied her up in the bathroom and put a gun to her head.

Kardashian, who her publicist said was "badly shaken but physically unharmed," said nothing to waiting media upon her arrival.

"What happened is very unfortunate and those responsible must be severely punished," French Foreign Minister Jean-Marc Ayrault told TV5 Monde. "We are fully mobilised to ensure the safety of the French people, as well as all those who visit France, and in particular tourists."

A Paris police source earlier told Reuters that five attackers, wearing ski masks and clothes with police markings, struck around 3am (10am AEST on Monday) inside the exclusive apartment block where Kardashian, 35, was staying while attending Paris Fashion Week.

Two of the men entered Carpathian's apartment after threatening the night guard with a handgun. Kardashian, who has two young children with Kanye West, was not beaten but the robbers put a handgun against her temple before tying her up, the source said. iTELE television said she had been tied up with packing tape.

E! News, whose US network broadcasts the Keeping Up With the Kardashians television show, on Monday quoted a source close to Kardashian as saying she feared for her life.

"She begged for them to let her live and (said) she has babies at home... She thought they were for sure going to kill her," the unidentified source told E! News.

The robbers stole a box containing jewels worth €5 million ($7.3 million) to €6 million and a ring worth about €4 million, the Paris police source said.

As news of the robbery spread, West abruptly ended a performance in New York less than an hour into his set on Sunday night.

Social media divided

The Paris apartment block is a discreet building behind the city's Madeleine church, with several secret entrances, often frequented by movie and music stars who pay up to €15,000.

The source said the attackers fled on bicycles. Police found the night guard in the staircase, his hand and feet bound.

Kardashian was in Paris with her mother, Kris Jenner, and sisters Kendall Jenner and Kourtney Kardashian to attend the fashion week. The rest of the family stayed in a hotel.

The robbery set social media alight, with some users making fun of the latest headline-grabbing event in the life of a TV star who documents her life continually on screen and on social media.

"Looking forward to accompanying album and TV show detailing event," said Twitter user Jay.

Most comments, however, were supportive. James Corden, the host of US talk show The Late Late Show, said on Twitter, "People making jokes about @KimKardashian tonight would do well to remember that she's a mother, a daughter, a wife, a friend. Be nice or shut up."

Paris has seen several armed robberies on high-end jewellery in recent months and the Kardashian incident could add to worries about safety in Paris, hit by a series of attacks by Islamist militants last year.

Paris traditionally is the most-visited city in the world, but tourist numbers fell 6.4 per cent in the first half of 2016 as many Asians and Americans stayed away.

"We worry about the image of Paris. This will be all over the news channels, imagine the negative publicity," Nathalie Kosciusko-Morizet, head of the conservative opposition in Paris, told Europe 1 radio.