A suspicious package sent to a Muslim MP at the Houses of Parliament is feared to be linked to "Punish a Muslim Day".
Mr Yasin became the MP for Bedford in last year's snap election after snatching the seat from Tory MP Richard Fuller.
"The letter calls for a day of violence against Muslims".
Police are investigating the "Punish a Muslim" letter, which has been distributed across the country, and details a list of violent acts alongside a number of points for performing them. "A man and a woman have been taken to a central London hospital as a precaution", a statement said.
Ms Huq tweeted: "Staffer who went to hospital now discharged". "It is to put the frighteners on us but we won't be cowed".
Bangladeshi-origin MPs Rushanara Ali and Rupa Huq and their Pakistani-origin colleagues Afzal Khan and Mohammad Yasin are the four Labour party MPs to receive the same kind of package in their parliamentary offices within the Palace of Westminster over the last two days.
"Tell MAMA documented past year how the so-called "Muslim Slayer" targeted mosques in parts of London and the United States in 2017 with similar threats, and in some cases, with non-toxic white powder".
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The people behind this initiative have not been identified yet, but their letters are distinguished by a hateful speech: "They have hurt you".
The letters, which are now being investigated by police, encourage people to get points for committing increasingly serious offences against Muslims.
Police said they were called at 12:58hrs to reports of a suspicious package at Norman Shaw Buildings, Victoria Embankment, Westminster.
Police are investigating after suspect packages containing anti-Muslim letters and a sticky liquid were sent to four Labour MPs over the past 24 hours.
"Sadly, it is reflective of hate against Muslims which continues to manifest itself alongside the rise of the far-right", said the council, which represents some 2.7 million British Muslims.
"The substance contained in it was deemed not to be hazardous to health", a Met police spokesman said on Monday.
'The incident, which was contained to one room, is in the process of being stood down'.