TOKYO - A member of parliament from Japan's ruling party called on Tuesday for Japanese Prime Minister Naoto Kan to step down as soon as possible, Kyodo news agency said, as pressure grows on the unpopular premier to resign or call a snap election.

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"It is important that Prime Minister Naoto Kan would resign as soon as possible," Kyodo quoted Kenko Matsuki, a Democratic Party of Japan (DPJ) lawmaker close to Kan rival and scandal-tainted powerbroker Ichiro Ozawa, as telling reporters.  

Matsuki's call underscores the difficulties facing Kan, who suffered a fresh blow this week when his foreign minister abruptly quit over a political donation scandal.

Kan is struggling to get a divided parliament to enact a $1 trillion budget for the fiscal year from April, while keeping his party from splintering.

Matsuki left his post as a parliamentary secretary in the Farm Ministry last month, saying he was unhappy with Kan's policy shifts such as a push for tax reforms that include a possible rise in the 5 percent sales tax.

Kan, whose public support rating has slumped to around 20 percent, said on Monday that he intended to stay on and some analysts have said he may be able cling to his post.  

But doubts remained over his ability to push key measures through parliament, including bills to implement the budget for the coming fiscal year and tax increases to address a public debt that is twice the size of Japan's $5 trillion economy.