* Eight countries still need to ratify test ban treaty
* Obama planning new push for pact rejected by Senate in 1999
* China, India, Iran and Israel among other holdouts
JAKARTA/VIENNA, Dec 6 (Reuters) - Indonesia’s parliament ratified a treaty to ban nuclear weapon tests on Tuesday, a move which the head of the agency set up to monitor the pact said brought it a “significant step closer to becoming global law.”
Adopted by consensus in the legislature, Indonesia’s endorsement makes it the 156th country to ratify the Comprehensive Nuclear Test Ban Treaty (CTBT).
The Asian state was among nine remaining countries -- including nuclear weapons powers the United States and China -- whose ratifications are required for the treaty that was negotiated in the mid-1990s to take effect.
“By this historic decision, the gap keeping the Treaty from entering into force has been narrowed down to eight countries,” Tibor Toth, executive secretary of the Comprehensive Test Ban Treaty Organization (CTBTO), said in a statement in Vienna.
There is widespread international support for the treaty but it cannot take effect until eight remaining so-called nuclear technology-holder states ratify it: the United States, China, India, Pakistan, Israel, Iran, North Korea, and Egypt.
Of that group, four states -- India, Pakistan, North Korea and Israel -- are outside the nuclear Non-Proliferation Treaty, the 1970 pact to prevent the spread of nuclear arms.
Iran is part of the NPT but the West accuses it of seeking to develop a capability to build atomic bombs. Tehran denies the charge and says its nuclear programme is aimed at producing electricity for peaceful purposes.
Proponents say U.S. ratification of the pact, which lawmakers rejected in 1999, could encourage other holdouts to sign on.
“The ratification by Indonesia today will hopefully give a push for nuclear-weapon owners to do the same,” Indonesian Foreign Minister Marty Natalegawa said in a statement.
The administration of U.S. President Barack Obama said in May that it was preparing a push for approval of the treaty, arguing that Washington no longer needs to conduct such tests but does need to stop other countries from conducting them.
But it has not given a precise time when it would seek a Senate vote on the treaty, which the chamber rejected when fellow Democrat Bill Clinton was president in the 1990s. A two-thirds majority would be needed for approval.
Obama, who will seek a second term next year, has made clear he sees the test ban pact as a step toward his vision of a world without nuclear weapons, like the new START arms reduction treaty the Senate approved last year.
At the time of the Senate vote 12 years ago, opponents argued that a permanent end to testing could erode the reliability of the U.S. nuclear arsenal. The country last carried out a test nearly 20 years ago.
Some also questioned whether cheaters could be detected.
Reporting by Olivia Rondonuwu in Jakarta; Writing and additional reporting by Fredrik Dahl in Vienna; Editing by Mark Heinrich