Mr Hatoyama said he felt a 'deep responsibility'
Japanese Prime Minister Yukio Hatoyama has apologised after two former aides were charged with violating the laws on political funding.
Prosecutors indicted the aides earlier on Thursday for misreporting millions of dollars of donations.
Analysts say the indictments are a big embarrassment for Mr Hatoyama's new government, which took power in August.
The prime minister said he felt "a deep responsibility" for what happened, but added that he would not resign.
Former aide Keiji Katsuba was charged with falsifying reports to make it appear that 360m yen ($3.9m) in donations to the ruling Democratic Party (DPJ) came from individual supporters, when in fact most of the money was given by Mr Hatoyama's family.
The prime minister's former chief accountant Daisuke Haga was also indicted - accused of failing to pay sufficient attention to the false reports - and has been ordered to pay a 300,000 yen fine, according to Jiji Press.
Both men were fired before Mr Hatoyama's election win over the Liberal Democratic Party (LDP) in August.
There is no suspicion of bribery because of the origin of the funds, and the prime minister himself is not expected to be charged.
He has said he had no idea about the misreporting of donations.
Mr Hatoyama hails from a wealthy family, sometimes dubbed Japan's version of the Kennedys. His mother is the eldest daughter of Bridgestone founder Shojiro Ishibashi and his grandfather was a former prime minister.
The scandal has been on the front pages of Japanese newspapers for days, and soon after the indictments were announced, Mr Hatoyama told a news conference: "I feel deep responsibility."
But he ruled out the possibility of resignation, saying: "I've decided I should not give up on myself nor my job."
A donations scandal forced Ichiro Ozawa, Mr Hatoyama's predecessor as leader of the DPJ, to step down from the post in May.
Amid continuing economic problems, Mr Hatoyama has already seen support for his government fall since the elections that brought him to power.
The DPJ is marking its 100th day in office on Thursday, but correspondents say the news of the indictments will give it little cause for celebration.