TOKYO (AFP) - Japanese Prime Minister Shinzo Abe said he plans to revamp his cabinet in early September for the first time since taking office, on the back of falling approval ratings.

"I want to reshuffle the cabinet and review the line-up of party executives in the first week of September," he told Japanese reporters accompanying him on a tour of Latin America on Thursday.

Nearly 600 days have passed since Mr Abe's conservative Liberal Democratic Party (LDP) swept back to power with an electoral landslide in December 2012, largely on a ticket to kickstart the long-lumbering economy.

"The LDP has talent in various areas. I will put the right people in the right places," Abe said, according to Japanese media reports from Santiago, Chile, the fourth leg of his five-nation tour.

The premier said he would try to keep women in the cabinet and key party posts as he looks to boost female workforce participation - part of a wider bid to breathe life into the world's number three economy.

Mr Abe declined to say if he would replace ministers in key posts.

The first power shake-up in 19 months could appease the frustration building among some LDP politicians, who have been yearning for cabinet posts since their party took back the reins of government after three years in the shadow of the centre-left Democratic Party of Japan, according to Japanese media.

In polls conducted by public broadcaster NHK and the Nikkei business daily, Mr Abe's approval rating has fallen 50 per cent for the first time since he took office. The rate hovered around 65 per cent in the early months of his administration.

The slide came as Mr Abe's government approved a controversial change to Japan's pacifist constitution last month that would give the military broader powers to defend allies.

There has also been strong public opposition to Mr Abe's bid to restart nuclear reactors shuttered after the 2011 Fukushima disaster.