LIMA (Reuters) - Peruvian President Pedro Pablo Kuczynski, a former investment banker who reported earning $700,000 per year before taking office in July, faced a wave of criticism on Friday for complaining about his salary as a public official.

Kuczynski's comments, posted online in a video by local daily newspaper Correo, come as his centrist government has been reeling from a corruption scandal involving a former adviser and deadly protests at one of the country's biggest copper mines.

The 78-year-old Oxford-and-Princeton-educated former World Bank economist was pitching a reform to raise the salaries of local mayors before he turned to his own earnings.

"The president of the Republic makes half of what a minister makes. There are two ministers here. Between the two of them they make four times what I make. Does that seem fair to you?" Kuczynski said before a group representing municipalities.

Kuczynski's office did not immediately respond to requests for comment.

Peruvians took to social media to deride the remarks, some drawing comparisons with three volunteer firemen who died this week trying to pull people from a fire near the outskirts of Lima.

"Before he said his dream was to become president to 'serve Peru.' Amnesia? Senior moment?' said Twitter user Rubem Dos Santos.

But some Twitter users said Kuczynski should be paid more than his ministers.

The president of Peru earns 15,600 soles ($4,588) per month before taxes. Cabinet ministers earn 30,000 soles per month. The minimum wage in Peru is 850 soles ($250).

Kuczynski reported annual earnings of 2,499,235 soles ($735,069) to electoral authorities before narrowly winning his the presidency in a June run-off.

Kuczynski's approval rating had risen to 63 percent in September before dropping 8 percentage points in the last poll by Ipsos, published on Sunday.

Kuczynski has vowed to put his ample experience in the private sector to work reviving investments in the global minerals exporter and ensuring all Peruvians have access to basic services.

($1=3.4 soles)

(Reporting by Mitra Taj; Editing by Leslie Adler)