New Delhi/UNI: The Central Bureau of Investigation (CBI) began a preliminary investigation on Wednesday into alleged improprieties in the construction and renovation of Delhi Chief Minister Arvind Kejriwal's new residence, sources in the federal agency said.

The CBI has requested documents related to the renovation of the Delhi CM's official bungalow; the sources said.

Bharatiya Janata Party's (BJP) Delhi unit has welcomed the central probe agency's move to probe the alleged irregularities.

BJP Delhi unit president Virendra Sachdeva claimed that Delhiites want to know from the CBI inquiry how Kejriwal got constructed a "Rajmahal" bungalow much bigger and above his entitlement.

"The inquiry will also bring out on whose instructions the PWD officials floated small tenders for the construction which was done without getting any sanction plan approved from the Municipal Corporation of Delhi and above all the rejection of the plan submitted to the Delhi Urban Art Commission," Sachdeva said.

Earlier, BJP had alleged that the Delhi CM spent Rs 45 crore on the decoration of his bungalow.

The BJP declared that Kejriwal had betrayed the "simple living" promise he made on entering politics.

Kejriwal's Aam Aadmi Party has accused the BJP of "using all its strength to destroy..." it.

"So far BJP has filed over 50 cases against Kejriwalji... nothing came out in them and nothing will come out of this. No matter how much investigation the BJP does, Arvind Kejriwal will continue to fight for the interests of the common man. Kejriwal has sworn he will make India No 1 in the world and he is ready to pay any price for this," a defiant AAP said in its statement.