People in terrorism-scarred Mumbai were among the voters trickling into polling stations early morning Thursday as balloting began in the third phase of India's month-long general elections.

Political stalwarts Sonia Gandhi of the Congress Party, which leads India's ruling coalition, and the opposition Bharatiya Janata Party's prime ministerial candidate Lal Krishna Advani are among the 1,567 candidates entering the fray in the third phase.

Balloting takes place in 107 parliamentary constituencies across nine states and two federally administered territories.

With searing summer temperatures across most of India, candidates are fearing a poor turnout.

"I hope the heat and the long weekend will not prevent people from casting their votes," Milind Deora, a young Congress Party candidate from the Mumbai South constituency, told the NDTV television channel as he set out to cast his vote.

Deora's constituency saw three days of mayhem in November 2008 when terrorists killed more than 170 people.

The residents' emotional reactions after the attack could lead to bringing out more voters, Deora said.

Security forces maintained tight watch in 10 parliamentary constituencies in the eastern states of Bihar and West Bengal which are located in areas affected by a Maoist insurgency and one constituency in militancy-hit Jammu and Kashmir holding polls on Thursday.

The Maoists and separatist political parties in Jammu and Kashmir have called for boycotting the elections.

Elections in the third phase are being held in Gujarat and Sikkim states and in parts of Uttar Pradesh, Bihar, Maharashtra, West Bengal, Karnataka, Jammu and Kashmir and Madhya Pradesh along with the federally administered territories of Dadra and Nagar Haveli as well as Daman and Diu.

Elections to the 32-member state legislature are being held simultaneously in Sikkim.

Results for all five phases of the elections that began on April 16 are due to be announced on May 16. (dpa)