PHNOM PENH (AGENCE FRANCE-PRESSE) - He has become the man without a face. In recent weeks Cambodia's beleaguered opposition has been frantically scrubbing images of their exiled leader Sam Rainsy from thousands of billboards and signposts across the country.

The mass pictorial purge was sparked by a controversial new law banning any political party from "using the voice, images or written documents" of anyone convicted of a crime.

The opposition Cambodian National Rescue Party (CNRP) believes the law was specifically designed to neuter the influence of Mr Rainsy ahead of next year's national elections.

The 68-year-old politician lives in self-imposed exile in France to escape a string of convictions that he says are politically motivated.

CNRP member Bunleng said he tore down his former boss' image from a large party banner erected in front of his home outside of the capital, Phnom Penh, last week.

"If we don't remove his image, there will be trouble for us, they would dissolve our party," the 59-year-old, who requested that only his first name be used, told AFP.

"Sam Rainsy is still inside people's hearts... His image will not fade away from people's hearts very quick," he added.

Cambodia has been ruled for the last 32 years by Mr Hun Sen, one of the world's longest-serving leaders.

He portrays himself as a premier who has brought growth and stability to an impoverished country ravaged by decades of war.

But critics say corruption, inequality and rights abuses have flourished under his watch.

Next year's elections are viewed by the opposition as perhaps the best opportunity they have ever had to unseat the strongman.

Under Mr Rainsy's leadership, they made significant gains at the polls in 2013 and did well in local elections earlier this year.

But the CNRP has also been hit by a slew of court cases as Mr Hun Sen and his Cambodian People's Party ramp up efforts to thwart their opponents.

Speaking from overseas, Mr Rainsy hit out at the new law which has led to his face being purged from the Cambodian landscape.

"Such a clumsy attempt at censorship will only make the party more popular and improve its chances of winning in 2018," he told AFP.

"I remain a symbol of resistance to the current regime and, in that sense, involved in politics," he added.

In February, Mr Rainsy resigned as official leader of the party, but remains its most prominent and influential figure.

Sebastian Strangio, author of a biography of Mr Hun Sen, said there was "a personal element to Rainsy's erasure from the Cambodian political scene".

"For a quarter-century, Rainsy has buzzed around, prodding at the CPP's legitimacy and questioning the benefits of Hun Sen's rule. I think Hun Sen simply got tired of it," he told AFP.

"But it seems unlikely that removing Sam Rainsy from CNRP signs will remove him from the memories of Cambodian voters," he added.