Democratic Party of Japan leader Naoto Kan, facing growing calls to resign over his failure to pay pension premiums, indicated to a DPJ executive Sunday that he will step down as head of the largest opposition party, party sources said.

"The term of office of the new leader should be the remainder of my term in accordance with party regulations," Kan was quoted as telling the executive, who urged Kan to resign soon, in a phone conversation.

On a television program earlier in the day, Kan said, "I'm fully aware of and taking (growing intraparty calls for resignation) very seriously."

His current term runs to September.

Party sources said support was mounting for Ichiro Ozawa, who holds the largely ceremonial post of acting DPJ president, to take the helm if Kan steps down. However, some party members dislike Ozawa's heavy-handed political tactics.

Speaking to reporters in the city of Shizuoka, Kan's predecessor, Yukio Hatayama, said Ozawa should serve as party leader in the event the post becomes vacant.

"This is only natural as part of the job of acting president," he said.

Those close to Ozawa, however, said it is unlikely the veteran lawmaker would agree to become party president as long as some within the DPJ oppose it. One insider suggested that the party not choose a successor for Kan and instead go into July's House of Councilors election with Ozawa still acting president.

DPJ lawmakers are scheduled to meet Monday over last week's agreement with the ruling coalition to revise the deadlocked pension reform bills.

Stressing the importance of having the DPJ's demands on pension reform included in the agreement, Kan suggested he will do his utmost at the meeting to win his party's approval of the accord.

The DPJ president said he will first explain to the public and the party why the accord is needed. Whether to step down is a separate matter, he added.

Some lawmakers, even within the DPJ, have criticized senior DPJ officials, including Kan, for approving the pension agreement with the ruling coalition.

Asked about speculation that Kan will agree to resign in exchange for obtaining the party's approval of the accord, he said, "No scenario has been written" over what to do.

Should the scheme be rejected, more heads could roll as other senior officials who worked to reach the agreement, such as Secretary General Katsuya Okada, may also be forced to take responsibility.

The ruling coalition and the DPJ agreed last week to add supplementary provisions to the government-sponsored pension reform legislation stipulating that the government will eye future unification of the public pension programs.

Eventual unification of the pension programs is one of the DPJ's key demands on the issue. Kan believes the accord will pave the way for this, but he conceded the latest accord does not necessarily guarantee unification in the near future.

The DPJ said the legislation does not represent full-scale reform, arguing it is aimed at increasing premium payments and reducing benefits.

Kan was found to have skipped 10 months of premium payments for the mandatory national pension in 1996, when he served as health and welfare minister.

Pressure for Kan to step down intensified after the resignation Friday of top government spokesman Yasuo Fukuda over his own failure to pay pension premiums.