What the papers say - March 6
Fears a former Russian double agent given refuge in Britain was "poisoned" in Salisbury lead most papers on Tuesday.
Sergei Skripal, 66, was convicted in 2006 of passing state secrets to MI6 before coming to the UK as part of a spy swap.
Police said officers were as yet "unable to ascertain" whether Skripal and a woman, 33, who were found unconscious on a bench near a shopping centre on Sunday, had been victims of a crime.
However, suspicions were growing that the incident was an attempted "hit" backed by the Kremlin, according to The Sun.
Meanwhile, the Daily Mail says Skripal had told agents "his life was in danger".
The i says the pensioner was "one of Britain's most important double agents".
A neighbour of Skripal told The Guardian that he had been living quietly in the area for more than seven years.
The Independent questions if Skripal was the victim of an attempted assassination similar to the killing of Alexander Litvinenko in London in 2006.
Georgia Pridham, 25, who saw the pair apparently unwell, told the Daily Telegraph: "He was quite smartly dressed. He had his palms up to the sky as if he was shrugging and was staring at the building in front of him. He had a woman sat next to him on the bench who was slumped on his shoulder."
Police are keeping an "open mind" over what caused the pair to fall ill, the Daily Mirror reports, alongside a striking image of an officer in a biohazard suit at the scene.
Scientists were deployed to decontaminate the area and the hospital where they are being treated, the Metro reports.
The Times reports neither had visible injuries and officers were working to identify the substance they had been exposed to.
The Financial Times also carries the story on its front page, alongside a lead report that the US is offering Britain a worse deal on aviation after Brexit than it currently has as part of the EU, which would hit British Airways and Virgin Atlantic.
The Daily Express features Skripal on its front page, but leads with former BBC Breakfast host Bill Turnbull's revelation that he has prostate cancer.