New Delhi, Nov 7 (IANS) More than half of the eligible seven million voters cast their ballot Saturday in by-elections to one Lok Sabha and 31 assembly constituencies across seven states, with the outcome set to have a bearing on almost all major political parties.

Officials reported serpentine queues in most balloting centres in the Firozabad parliamentary constituency of Uttar Pradesh as well as the state's 11 assembly seats.

The same was the case in West Bengal (10 assembly seats), Kerala (3), Rajasthan, Assam and Himachal Pradesh (2 each) and Chhattisgarh (1).

The voting percentage ranged from 50 in Chhattisgarh to a high of 80 in Kerala.

The exercise passed off peacefully barring minor incidents of violence in West Bengal, election officials said. It was the first popularity test after last month's assembly polls in Maharashtra, Haryana and Arunachal Pradesh that produced mixed results for the Congress.

Saturday's battle was politically most crucial in Uttar Pradesh and West Bengal, where the Left Front is on the defensive in the face of an aggressive Trinamool Congress and rising Maoist violence.

An estimated 53.5 percent of the electorate voted in Firozabad, where Congress candidate and movie star Raj Babbar has taken on Dimple Yadav, daughter-in-law of Samajwadi Party chief and former Uttar Pradesh chief minister Mulayam Singh Yadav, making it a battle of prestige.

Although the Bharatiya Janata Party (BJP) and Uttar Pradesh's ruling Bahujan Samaj Party (BSP) are also in the fray, the Congress and the Samajwadi Party are the main players in the constituency.

The results of the by-elections will be keenly watched in Uttar Pradesh, where Chief Minister and BSP chief Mayawati has no friends.

Apart from Uttar Pradesh and Left-ruled Kerala and West Bengal, the Congress or BJP govern the other four states.

Amid tight security, brisk voting was reported almost everywhere.

Nearly 50 percent voted in the 11 Uttar Pradesh seats of Powayan (SC), Lucknow West, Padrouna, Rari, Isauli, Jhansi, Kolasala, Hainsar Bazar, Lalitpur, Etawah and Bharthana. Some 4.9 million voters were eligible to vote in Uttar Pradesh.

About 65 percent voting took place in West Bengal, where elections have become a do-or-die battle for the ruling Left Front led by the Communist Party of India-Marxist (CPI-M).

The 10 seats are Kalchini (ST), Rajganj (SC), Sujapur, Goalpokhar, Bongaon, Contai South, Egra, Serampore, Alipore and Belgachia East,

The Marxists had suffered a humiliating defeat in the May Lok Sabha election and have fared poorly in all subsequent elections in the state.

To add to the Left's woes, most of Saturday's constituencies are known as opposition citadels. Seven of the seats had elected Trinamool or Congress candidates even during the Left sweep of 2006.

Peaceful balloting was reported in Kerala's three assembly seats, the voting percentage varying from 64 in Ernakulam to 76 in Alappuzha to 80 in Kannur. In Kannur, the Congress fielded A.P. Abdulla Kutty, who until early this year was a two-time CPI-M MP. The Marxist candidate there is heavyweight M.V. Jayarajan.

Rajasthan's two assembly seats of Todabhim and Salumbar reported 50 percent polling. Assam's Salmara South and Dhekiajuli saw 65 percent voting. The figure stood at 68 percent for Himachal Pradesh's Rohru and Jawali constituencies.

Chhattisgarh's Vaishali Nagar constituency saw 50-55 percent balloting.