Despite protests from Japan and its allies, North Korea may be preparing another ballistic missile launch, Chief Cabinet Secretary Hiromu Nonaka said Thursday, quoting intelligence reports.

If Pyongyang fired the first shot Monday in an effort to boost morale at home, then its convening of Parliament on Saturday and its national day next Wednesday will be key dates to watch, especially with the election of Kim Jong Il as president expected shortly, Nonaka said at a regular news conference.

The top government spokesman acknowledged that Japan has obtained information Pyongyang might be preparing to fire another missile, although the data has not been confirmed. The government "needs to further strengthen its precaution and defense" in order to prepare Japan for all possibilities, Nonaka told the press.

But Nonaka also expressed doubts from a technical perspective about Pyongyang firing a second missile soon.

A government source said late Wednesday that a second missile firing by North Korea would probably be a test of a short-range ballistic missile.

The source said the government has dispatched Maritime Self-Defense Force ships to the Sea of Japan to be on the alert, though information from U.S. forces shows that there are no signs of another missile launch.

Meanwhile, South Korea's Yonhap News Agency reported that Seoul has detected moves indicating North Korea is preparing to launch another missile.