Thousands of people in Thailand took part in early voting on Sunday a week ahead of general elections which will be the first in the country since the army seized power in a bloodless coup in 2014.

Around two million voters registered to take part in the early voting process ahead of the March 24 general election, 900,000 of them in Bangkok, where they stood in long queues waiting for the polling booths to open.

Former Prime Minister and president of the Privy Council, General Prem Tinsulanonda, 98, was among those who cast their vote along with other military and police personnel, besides civilians who will not be able to be present at their electoral districts on March 24.

Around 50 million Thai people are eligible to vote next Sunday, nearly five years after the army held a coup following months of street protests.

During its rule, the military junta carried out a comprehensive legal reform, including the Constitution, restricting the scope of elected government and consolidating the role of the army in the political life of the country.

The elections, which were postponed several times by the military junta, will be held to elect 500 members of the House of Representatives - the lower house.

Some 375 of them will be chosen directly through constituency elections, while 125 will be elected through party-list proportional representation.

Head of the military junta and current Prime Minister Prayut Chan-ocha has been nominated by the Phalang Pracharat, a pro-military party, as its prime ministerial candidate in the elections.

The Pheu Thai party, which was overthrown from power during the last coup, is expected to be the main rival of the Phalang Pracharat.

Pheu Thai represents the political movement led by former Prime Minister Thaksin Shinawatra and has won all the elections held in the country since 2001.

Thaksin Shinawatra's enormous popularity is largely thanks to his approval of universal healthcare and soft loans for farmers in 2001 to alleviate inequality, which earned him massive support from rural areas and working classes.

Pitted against him were the wealthiest classes and the elites close to the monarchy and the army, who ousted him in a rebellion in 2006 and toppled the government led by Thaksin's sister, Yingluck Shinawatra, in 2014.

Both of these former prime ministers have been sentenced to prison imposed in absentia for corruption, charges which they say are trumped up as an act of political revenge by the Bangkok elites.

In 2013 and 2014, Thailand witnessed massive street protests by both anti-Thaksin and pro-royalist Yellow Shirts and the and pro-Thaksin supporters, dubbed the Red Shirts.