Chief Cabinet Secretary Shinzo Abe is considering tougher measures against North Korea than those adopted by Junichiro Koizumi if he becomes prime minister next month, hoping to help settle the issue of Japanese abductions, government sources said Sunday.

As prime minister, Abe would boost the power of a government task force on the abductions and push ahead with new measures for economic sanctions in cooperation with the ruling coalition parties, the sources said.

They said these plans would represent a policy shift from Koizumi's "dialogue and pressure" against North Korea to one stressing "pressure."

According to media polls, the 51-year-old Abe is the most popular candidate to succeed Koizumi both among the public and among LDP members, who will actually make the selection.

Abe will likely urge North Korea to refrain from conducting an underground nuclear test by taking a clear position that Japan will seek U.N. Security Council authorization for sanctions, the sources said. This is in connection with a recent report that North Korea may be preparing for such a test.

The Security Council unanimously adopted a resolution last month condemning North Korea's launch of seven ballistic missiles on July 5. The resolution fell short of calling for sanctions.

North Korea rejected the resolution and refuses to return to the deadlocked six-nation talks with the U.S., China, South Korea, Japan and Russia.

Abe is mulling the hardline approach because of Pyongyang's defiant reactions and a lack of progress in relations under the Koizumi administration, the source said.

They said he is thinking of having Japan strengthen cooperation with other countries, such as the U.S., in implementing the U.N. resolution and preventing transfer of materials, technologies and funds related to Pyongyang's missile development.