Cambodia's newly pardoned opposition leader Sam Rainsy returned home on Friday to join his party's election campaign to end Prime Minister Hun Sen's three decades in power.

At least 30,000 supporters greeted Rainsy at Phnom Penh's airport, shouting "b'do!", or "change!", the campaign slogan of his Cambodia National Rescue Party (CNRP). Thousands more lined Rainsy's route into the city center.

The CNRP draws much of its support from among poorer Cambodians and those who suffered under the regime of the Khmer Rouge.

Rainsy was given a royal pardon last week by King Norodom Sihamoni at the request of his rival Hun Sen.

The French-educated Rainsy, 64, who was a labor activist in the mid-1990s, had been in exile since 2009 to avoid serving prison sentences in Cambodia. The US-based Human Rights Watch had described charges previously brought against him, such as spreading disinformation, as politically motivated.

The US, the EU and other nations had warned that an exclusion of Rainsy would damage the election's legitimacy.

Rainsy to 'galvanize' campaign

Rainsy, who without a Cambodian electoral change is not allowed to run as a candidate, is likely to push the issues of corruption and land grabbing among Cambodians in poor, rural areas.

A spokesman for Rainsy's CNRP, Yim Sovann, said the party would discuss ways to register Rainsy as a candidate.

"His presence will galvanize activists and voters," said Sovann.

Hun Sen, 61, is likely to win the upcoming election, according to analysts. His Cambodian People's Party (CPP) has 90 of the 123 seats in Cambodia's National Assembly, and he recently said he intended to stay in office until the age of 74.

On June 8, a CPP-dominated committee expelled 29 opposition lawmakers from parliament, claiming they were ineligible to sit because the parties for which they were elected no longer existed.

The July 28 poll will be the fifth parliamentary election since the United Nations brokered a peace deal for Cambodia in 1991. That arrangement was meant to end decades of bloodshed that included the communist Khmer Rouge's 1975-79 rule.

An estimated 1.7 million people died in torture centers, labor camps and from starvation and disease.

Hun Sen is a former Khmer Rouge member, but his party has not been linked to any of the former regime's alleged human rights abuses.

ipj/pfd (AP, Reuters, AFP, dpa)