Lima: Peru's President Pedro Pablo Kuczynski offered to resign on Wednesday after vote-buying allegations ensnared his centre-right government on the eve of an impeachment vote, capping months of political turmoil in one of Latin America's most stable economies.

Kuczynski, a 79-year-old former Wall Street banker who once held US citizenship, promised a constitutional and orderly transition of power and blamed his departure on the opposition's persistent efforts to depict him as corrupt.

"The best for the country is that I resign as president of the republic, because I don't want to be an obstacle for the nation's search for a path to unity and harmony," Kuczynski said in a pre-recorded speech that was televised after he departed the presidential palace in a car.

Even some of his staunchest defenders called for him to step down, although opposition lawmakers signalled they might not accept his resignation.