Manish Sisodia, Delhi's Deputy Chief Minister, has alleged the Lieutenant Governor has been making "politically motivated" decisions by ordering investigations into different issues one after another.
Mr Sisodia's comments came hours after Lieutenant Governor VK Saxena told the Chief Secretary to probe "irregularities and discrepancies" in the power subsidy given by Chief Minister Arvind Kejriwal's Aam Aadmi Party government, and give a report in seven days.
Mr Saxena ordered the new investigation about three months after he allowed a CBI probe into Delhi's liquor policy, a case in which Mr Sisodia is an accused.
In a letter to the Lieutenant Governor, Mr Sisodia told Mr Saxena he has been bypassing Delhi's elected government and ordering "illegal and unconstitutional" investigations.
"You have no right to give orders in any matter other than land, police, public order and services," Mr Sisodia wrote in the letter.
"All your orders are politically motivated. So far nothing has come out in any of the investigations. I request you to act according to the Constitution," the AAP leader said.
Delhi Chief Minister Arvind Kejriwal, in a swipe at the investigation order into the AAP's power subsidy scheme, said the latest probe order was a BJP move against the AAP's expansion. "Gujarat is liking the free electricity guarantee by AAP," Mr Kejriwal tweeted. "That's why BJP wants to stop free electricity in Delhi," he said.
Gujarat, Prime Minister Narendra Modi's home state where the BJP has been in power for over two decades, has elections later this year. The AAP is targeting it as its third base after Delhi and Punjab.
The alleged scam in Delhi's power subsidy is linked to payments by the state government to companies that supply electricity in the city.
Delhi has 58 lakh domestic power consumers, of whom 47 lakh use the subsidy - including 30 lakh who get no bills as consumption of less than 200 units is free. About 17 lakh get a 50-per cent subsidy, which is for consumption of up to 400 units. The government pays the companies for this.
In July, the Delhi Lieutenant Governor ordered a CBI inquiry into the now-withdrawn excise policy that had brought private players into the liquor trade in the national capital.