Tens of thousands of people lined the streets to give a rapturous welcome on Saturday to Myanmar Nobel laureate Aung San Suu Kyi as she hit the campaign trail for the first time in her bid to win a seat in the country's parliament.

Riding in a convoy of three dozen cars and flanked by hundreds of motorcycles, Suu Kyi received rock star treatment from crowds of cheering, flag-waving supporters chanting long live mother Suu throughout her seven-hour crawl to the rustic constituency where she will contest April by-elections.

The leader of Myanmar's pro-democracy struggle stood through a car sunroof, waving and smiling as dilapidated, overloaded trucks shuttled in the crowds, in an outpouring of excitement at a rare rally in a country tightly controlled for 49 years by an army that brutally suppressed activism.

We need your strength, for the people, Suu Kyi shouted to the crowd, much of which held aloft her picture alongside that of her late father and independence hero, Aung San who was assassinated when his daughter was two years old.

The decision to contest the by-election represents a giant leap of faith for Suu Kyi and her National League for Democracy (NLD) party after two decades being jailed, harassed and sidelined by the former junta, which made way to a nominally civilian government 11 months ago.

The NLD boycotted the widely flawed 2010 election but last year accepted an olive branch from president and former junta fourth-in-command, Thein Sein, who reached out to Suu Kyi. She regards the reform-minded ex-general as sincere and trustworthy.

The motorcade moved at a snail's pace on a 56-km (35-mile) venture south of the commercial capital Yangon, weaving through bamboo-hut villages on bumpy, dusty dirt-tracks as farmers and children jostled to catch a glimpse of The Lady, as she is affectionately known.

Some 5,000 supporters in Warthinkha, a village of just 1,000 people, packed into a rice paddy to hear her rousing speech on a makeshift stage, her voice drowned out by bursts of applause.

'ALL-OUT EFFORT'

I call on the people to have confidence in us. The NLD has no magic power, but we will get to our desires soon with an all-out concerted effort, with the courage and ability to get over the struggle, Suu Kyi told the crowd.

There are so many struggles ahead, I recognise this not because I'm disappointed but just to say we need strength and reinforcement to overcome them.

The journey we are on, with the people, is very rough but the destination we are headed for is peaceful.

Her bid for a parliamentary role is largely symbolic, with only 48 seats up for grabs in the by-elections, meaning the NLD can only secure a tiny stake in the national legislature.

The last time the party contested an election was in 1990, when its landslide win was ignored by the junta. Suu Kyi did not run in the poll because she was under house arrest.

It remains to be seen exactly what Suu Kyi could achieve in a parliament stacked with military appointees and lawmakers allied with a party widely believed to have been formed and funded by the ruling generals before they stepped aside.

But the farmers who turned out in their droves believe Suu Kyi can be the decisive factor in transforming the country.

I've never seen such a huge crowd. We're very lucky she's decided to stand in the election representing our village, said mother of four, Naw Ohn Kyi, 59. It's like we've won the biggest prize in the lottery without even buying a ticket.

Another villager, Sa San Thein, 35, added: We were thrilled to hear Aunty Suu was coming. It's just like a mother who left on a long journey, coming home unexpectedly.

The elections will be closely watched by the international community as a litmus test of the government's sincerity towards reforms, which have included the release of an estimated 650 political prisoners and ceasefires with ethnic rebel armies.

Diplomats expect the polls will be free and fair, despite irregularities in the 2010 election, because the participation of Suu Kyi, the charismatic darling of the West, would be a powerful endorsement of its fledgling democratic system.

A clean poll is also a pre-requisite for lifting of sanctions that are currently under review, as Western nations seek to bring the vastly underdeveloped but resource-rich country out from the cold after two decades of isolation.

(Writing by Martin Petty; Editing by Ed Lane)