Scores more imams and Muslim religious leaders have said they will not perform funeral prayers for the perpetrators of the London Bridge attack, bringing the number of signatories to a statement to more than 200.

The grassroots, cross-denominational initiative from imams, teachers, chaplains and other religious figures is intended to send a strong message to extremists considering acts of terror in the name of Islam.

“We decided we needed to make a public statement, to send a strong message – effectively, you’re not welcome in our community either in life or in death,” said Qari Asim, imam at the Makkah mosque in Leeds.

“This decision was not taken lightly. One of the last things you offer to the deceased is to seek forgiveness for them from God. By not performing the funeral prayer, we are not asking for forgiveness.

“The gravity of the crime is such that we feel it should be clear to young people that we cannot offer the prayer, though it is up to God to judge [the attackers].”

Yunus Dudhwala, the head of chaplaincy at St Bartholomew’s hospital in central London, said it was unprecedented for so many imams and religious leaders to unite around such a statement. “Down on the ground, we have the ear of the community, and people know these killers have nothing to do with Islam,” he said.

“It is written as one of the rules [of Islam] that funeral prayers should be performed. In cases where people have perpetrated heinous crimes against humanity, there are precedents were religious leaders decline to say prayers. But it is rare.”

The imams’ statement did not rule out funeral services being held for the perpetrators, he added. “The families could do a private funeral. But these people don’t deserve our prayers.”

The statement was intended to deter extremists who believe that acts of jihad will be rewarded in the hereafter, said Rehanah Sadiq, an Islamic teacher. “We want to make it clear this is not the case. If these people know that imams and teachers are not going to pray or ask forgiveness for them, they might question what they are about to do.”

She added that it was an Islamic duty to care for the families of the attackers. “The families should not be ostracised – that would be sinful or wrong from an Islamic perspective. Every individual is accountable for his or her deeds. No one else is responsible. This must be incredibly painful for the families.”

Asim said the attackers were “not martyrs but criminals. These so-called jihadists are not fighting a holy war.” Jihad means struggle, which could be personal, social or political, he added.

“Jihad is a religious term misused by terrorists and misunderstood by the wider public. Terrorists are using the term to destroy our values in society.”