Local government secretary Sajid Javid has become the fifth politician to receive a hate-filled anti-Muslim letter.
The ‘Punish a Muslim Day’ letter calls on the public to abuse or attack Muslims, awarding ‘points’ for the sickening acts.
Mr Javid - who posted an image of the letter on social media - is the fifth MP to have received the abuse in the post.
Rupa Huq, Rushanara Ali, Mohammad Yasin and Afzal Khan have also received letters in the past week.
The Government has condemned the ‘abhorrent’ hate campaign and said it would refresh its Hate Crime Action Plan later this year.
Counter terrorism police and local police forces across the country are investigating.
Detective chief superintendent Martin Snowden, head of Counter Terrorism Policing North East, said: 'We take religious hatred extremely seriously and my officers will be carrying out a full and thorough investigation in response to these reports.
''These letters seek to cause fear and offence among our Muslim communities. They also seek to divide us. Yet in spite of this our communities have shown strength in their response to such hatred and in their support for each other.'