The Anti-Corruption Branch (ACB) is carrying out an on-site inspection of the projects under its scanner in relation to its probe into an alleged scam in the Public Works Department (PWD).
Three separate FIRs have been registered by the anti- graft body in connection with the "scam", including one against a company owned by Delhi Chief Minister Arvind Kejriwal's brother-in-law Surender Kumar Bansal, who passed away recently.
According to ACB chief Mukesh Kumar Meena, a site inspection is going on of the projects in north-west Delhi, for which contracts were awarded to these three companies, to collect evidence.
The ACB has already questioned PWD officials in connection with the matter.
The FIRs were registered on the basis of a complaint filed by the founder of the Roads Anti-Corruption Organisation (RACO), Rahul Sharma, who alleged irregularities in the grant of contracts for roads and sewer lines in Delhi in 2015-16.
Subsequently, Sharma lodged another complaint with the ACB alleging that he had been receiving threats ever since he filed the first complaint.
The FIR names three companies, of which Renu Constructions is owned by Bansal, while the other two are owned by Kamal Singh and Pawan Kumar respectively.
The ACB had raided the PWD office last week and took away a few files.
Sharma, the complainant, has also been questioned by the probe agency.
The development comes in the backdrop of corruption allegations levelled by sacked Delhi minister Kapil Mishra against Aam Aadmi Party (AAP) supremo Kejriwal.
RACO, a non-governmental organisation (NGO) which claims to monitor construction projects in the national capital, had alleged that a firm linked to Bansal was involved in financial irregularities in constructing a drainage system in north-west Delhi.
It had also alleged that the bills sent to the PWD for the "incomplete" works were "false and fabricated".
Sharma had alleged that in April 2015, Renu Construction was awarded the contract to construct a drainage system in north-west Delhi's Bakoli village.
"In 2015-16, the company obtained a contract for works which were never completed, but the payments were cleared. Even the bid was manipulated," the complaint, dated January 9, read.
The invoices pertaining to the project, purportedly obtained by RACO from the PWD through an Right to Information (RTI) application, were sent to the Sales Tax department for verification.
Sharma had alleged that the Sales Tax department had informed in writing that the invoices were false and fabricated.