The 18.6km northern section of Line 2 will include 17 new stations and will link an interchange with Line 1 at DN Nagar with Charkop and Dahisar East. The total budget for the project is estimated to be Rs 64.1bn ($US 988m).
The second project is a Rs 62.1bn 16.5km link between Dahisar East and Andheri East, which will have 16 stations. Both projects are due to be completed by March 2019.
India's prime minister Mr Narendra Modi is expected lay a foundation stone for both projects during a visit to Mumbai on October 11.
The city's first metro line, which runs east-west from Versova to Ghatkopar was inaugurated in June 2014 and construction is underway on the 33km north-south Line 3 from Santa Cruz Electronic Export Processing Zone to Bandra and Colaba, which is expected to open in 2021.