Cambodia's self-exiled opposition leader says he will return to his homeland on July 19, less than two weeks before his beleaguered party challenges entrenched Prime Minister Hun Sen in national polls.

Sam Rainsy announced the date of his intended return on his Facebook page on Saturday, a day after Hun Sen engineered a pardon for his most prominent rival. Fellow party members gave the same date.

The pardon cleared the way for Sam Rainsy to return home to campaign for his party without facing immediate arrest and imprisonment.

His return is not likely to greatly affect the big picture at the polls, where Hun Sen appears assured of extending his 28-year rule.