LONDON — Police scoured the area around Salisbury, England, for a container of a deadly chemical weapon on Monday, as high-ranking British officials suggested for the first time that Russia was probably responsible for a second set of nerve agent poisonings in the region.

British officials have said that a couple who were sickened this month in the Salisbury area, one of whom died Sunday, had been poisoned with the same powerful nerve agent used in March, a few miles away, against a former Russian spy and his daughter.

But while government officials have accused the Kremlin of the first poisonings, until Monday they had refrained from assigning blame for the second.

“The simple reality is that Russia has committed an attack on British soil, which has seen the death of a British citizen,’’ the defense minister, Gavin Williamson, said. “That is something that I think the world will unite with us in actually condemning.’’

Sajid Javid, the home secretary, who has acted as the government’s spokesman on the matter, was more cautious in addressing Parliament. The investigation is underway, he said, and the government will not jump to conclusions.

But when asked directly if Russia was responsible for the latest poisonings, he said it was hard to see any other plausible explanation.

Dawn Sturgess, 44, and her boyfriend, Charlie Rowley, 45, became ill on June 30 at Rowley’s home in Amesbury and were hospitalized. Sturgessdied Sunday, and the case is now a murder investigation.

They had been exposed to an agent known as Novichok,

The government of Russia has denied any involvement in either case, floating an array of theories about what might have happened and nominating an assortment of possible culprits.

NEW YORK TIMES