The requests will be considered by the Board of Approval (BoA), headed by Commerce Secretary Rajeev Kher, on March 10.
Other developers that have sought additional time include Alstom Bharat Forge Power, Sesa Sterlite Ltd and Cognizant Technology Solutions.
Vedanta Aluminium has asked for extension of the validity of the approval granted by the board for setting up an SEZ in Odisha beyond May 22.
"The developer has requested for further extension by one more year. Development Commissioner (DC) has recommended the proposal for extension for one year, considering the advanced status of the project and steps taken by the developer," according to the agenda of the BoA.
The approval given to Dr Reddy's Laboratories ended on February 26 and it "has requested for further extension so as to implement the project."
The company is setting up a pharma SEZ in Andhra Pradesh and has invested Rs 150 crore on infrastructure facilities in the project, it said.
Tata Consultancy Services has sought extension of its Letter of Permission beyond April 23.
According to an industry expert, besides the global slowdown, uncertainty over tax exemptions to new SEZs has led to declining interest in such projects. Investors are apprehensive about the proposed Direct Taxes Code (DTC).
According to the revised DTC draft, which will replace the Income Tax Act of 1961, tax exemptions for SEZs will be confined to existing units.
SEZs have emerged as a major route for attracting investment and increasing exports. The government has also announced an incentive package to revive investor sentiment.
So far, 577 SEZs have been formally approved, of which 173 are in operation.
SEZs contributed over 25 per cent to the country's exports. Overseas shipments from these zones stood at Rs 5.56 lakh crore in 2012-13.