Amnesty International says it has “credible reports” that Sudanese police have killed 37 protesters in clashes during anti-government demonstrations that erupted last week across much of the country.

In a statement late Monday, the London-based rights group said the use of lethal force by security forces against unarmed protesters was “extremely troubling” given that more protests were planned Tuesday.

A coalition of independent professional unions has called for a march on the presidential palace in Khartoum later Tuesday to submit a petition demanding that longtime autocrat Omar Bashir step down. Two of Sudan’s largest political parties called on their supporters to take part.

The protests began last Wednesday, initially over rising prices and shortages of food and fuel, but later escalated into calls for Bashir to go.

In this Friday Dec. 21, 2018 handout photo provided by a Sudanese activist, people pray in front of the bodies of 14-year old Mohammed Ismail and 10-year old Shawky Sadeq who were both killed during an anti-government protest, during their funeral procession, in Aba Island, on the White Nile, south of Khartoum, Sudan. (Sudanese Activist via AP)
In this Friday Dec. 21, 2018 handout photo provided by a Sudanese activist, people pray in front of the bodies of 14-year old Mohammed Ismail and 10-year old Shawky Sadeq who were both killed during an anti-government protest, during their funeral procession, in Aba Island, on the White Nile, south of Khartoum, Sudan. (Sudanese Activist via AP)
In this undated handout image provided by a Sudanese activist, an injured protester receives treatment at a hospital in Khartoum, Sudan. (Sudanese Activist via AP)
In this undated handout image provided by a Sudanese activist, an injured protester receives treatment at a hospital in Khartoum, Sudan. (Sudanese Activist via AP)
In this Thursday, Dec. 20, 2018 handout photo provided by a Sudanese activist, protesters chant slogans during a demonstration, in Khartoum, Sudan. (Sudanese Activist via AP)
In this Thursday, Dec. 20, 2018 handout photo provided by a Sudanese activist, protesters chant slogans during a demonstration, in Khartoum, Sudan. (Sudanese Activist via AP)

Source: The Associated Press