London: Police and ambulance crews have been called to parliament after a suspicious package was delivered to an office, days after four Muslim Labour MPs were sent similar packages with anti-Islam messages.

A Metropolitan police statement said officers were called to Westminster just before 10.15am on Thursday after reports of the suspicious package.

“Specialist officers are on scene and the package is being assessed,” it said. “London ambulance service is on the scene. A woman is being assessed as a precaution. Inquiries continue.”

During Monday and Tuesday, the four Muslim Labour MPs were sent packages including copies of a “Punish a Muslim” letter, which advocates violent acts against Muslims.

The MP for Ealing Central and Acton, Rupa Huq, was the last of the four to receive the letter, copies of which are also understood to have been opened by staff for Rushanara Ali (Bethnal Green and Bow) and Mohammad Yasin (Bedford).

A fourth package was sent to the Manchester Gorton MP, Afzal Khan, but was not opened.

Commons authorities confirmed another package had been received but gave no further details.

A Labour party spokesman said he did not know about the latest package, and had no information about whether it might also have been sent to one of the party’s MPs.

A member of Huq’s staff was taken to hospital as a precaution after opening the letter, which the MP said contained a “sticky substance” that the police had described as “low-level noxious”.

On Monday two people were taken to hospital, also as a precaution, when a package leaking a suspicious liquid was sent to Yasin’s office.

All four suspicious letters sent to MPs have been found in the Norman Shaw north building in Westminster, which houses MPs’ offices and is linked by a walkway to Portcullis House.

On Thursday the ambulance and police were gathered in an inner courtyard of the main parliament building, indicating the package was delivered to an office there.

Police are investigating the “Punish a Muslim” letter, which has been distributed across the country and gives a list of violent acts alongside numbers of points for performing them. Tell Mama UK, which monitors anti-Muslim hate crimes, said it had received reports of people in Bradford, Leicester, London, Cardiff and Sheffield getting the letters.