Arrest former premier Dr Mahathir Mohamad - inspector general of police Khalid Abu Bakar was dared today.

Former Umno supreme council member Saifuddin Abdullah threw this challenge down in a tweet to the IGP.

Prime Minister Najib Abdul Razak had accused Mahathir of masterminding allegations of wrongdoing regarding 1MDB's against him and Saifuddin asserted this was enough for the IGP to act.

"The prime minister said Dr. Mahathir is the mastermind, what else, @KBAB51, go and arrest. Go PDRM go," urged Saifuddin, who also asked for: “All sorts of investigations:  for the truth, to instill fear, to blacken, to whitewash."

Najib had threatened to use the "full force of law" against critics who had accused him of stealing state funds.

The premier had issued the ultimatum after accusing Mahathir of masterminding the criticisms against him.

"Those who continue to mount these attacks should be prepared to face the consequences of their actions.

"These gutter tactics - in some cases, criminal tactics - to overthrow the government will fail.

"Where appropriate, they will be met with the full force of the law," Najib had said.

The premier was responding to aWall Street Journal (WSJ) report on July 3, which alleged that US$700 million (RM2.6 billion) of 1MDB's funds was deposited into the prime minister's private accounts.

Saifuddin (photo) had been quite vocal on 1MDB's fiasco, where he had urged the prime minister to address the latest scandal on "live" TV.

"Since school I never withdrew at the last minute if I have confirmed my attendance at a dialogue, forum or debate," he wrote sarcastically when Najib failed to appear at a recent dialoque session, dubbed 'Nothing to hide'.