Detectives have interviewed a couple at the centre of a fresh poisoning scare in Salisbury amid growing suspicion that the incident was a hoax.

Alex King and Russian-born Anna Shapiro were taken to hospital on Sunday evening after apparently falling ill at an Italian restaurant. A major incident was declared and the pair were tested for exposure to novichok, but medics quickly established they had not been the victims of a nerve agent attack.

In a front-page story published in the Sun newspaper on Wednesday, Shapiro, a model and events manager, claimed they had been targeted by Moscow, six months after the former spy Sergei Skripal was attacked with novichok in the cathedral city.

The Sun reported that King was in a life-threatening condition and suggested he may have been poisoned with strychnine. By Wednesday evening, however, the story was beginning to unravel as Salisbury district hospital released a statement saying both patients involved in the incident had been discharged and police sources said officers were looking into the possibility that the incident was a hoax.

A Wiltshire police spokesperson said on Thursday: “We can confirm that both people have been interviewed and our inquiries are ongoing. We would ask the media not to speculate whilst these inquiries are ongoing.” No arrests have been made.

The incident was a further blow to Salisbury, which has been struggling to recover from the attack on Skripal and his daughter, Yulia, and the subsequent nerve agent poisonings of a local couple, Charlie Rowley and Dawn Sturgess. If it does turn out to have been a hoax, there will be fury in the city.

The Sun’s original story about Shapiro’s claims was unavailable on its website on Thursday morning. A message said this was “for legal reasons”.

The newspaper has refused to say whether it paid Shapiro for the story. A Sun spokesperson said: “Like any newspaper, we were keen to talk to those at the centre of the incident and in this case chose to give Ms Shapiro the opportunity to share with the public her version of events.

“Given recent tragic events in Salisbury, the reporting of an event requiring the evacuation of bars and restaurants … and that requires tests for the presence of novichok is of obvious public interest.”

Shapiro and King are friends of Edward Davenport, nicknamed “Fast Eddy”, who is famed for throwing parties at a central London mansion attended by rock stars and film actors – and for being jailed for fraud. King used to act as Davenport’s “press representative”.

Davenport described King as a “fun guy” and told how in 2006 King won a £100,000 bet to get into a royal premiere and shake hands with Prince Charles. The Telegraph described King then as a “prankster”.