Besides asking the four to be present in the court on September 6, Special Judge Sangita Dhingra Sehgal also issued production warrant against Amar Singh's former aide Sanjeev Saxena and alleged BJP activist Suhail Hindustani who were arrested earlier and presently lodged in Tihar Jail.
The court sought the presence of the six accused including the two former BJP MPs Faggan Singh Kulaste and Mahabir Singh Bhagora before it, taking cognisance of the Delhi police charge sheet, filed in the case on Wednesday before it.
"I take cognisance of all the offences mentioned in the charge sheet," the judge said.
Delhi Police, in its charge sheet, had indicted all six for their roles in the scam, involving payment of bribes to some MPs to win their votes in a trust motion, piloted by the Congress-led UPA government.
While issuing summons to Amar Singh, Kulkarni, Kulaste and Bhagora, the judge also asked police as to why they were not arrested earlier along with the two other accused.
"Is there any special reason for not arresting them," the judge asked.
Public Prosecutor Rajeev Mohan, appearing for the Crime Branch of Delhi police, told the court that the four were not arrested as their custodial interrogation was not required.
Mohan, however, requested the judge to take cognizance and issue summons against all the six accused.