BEIJING, July 15 (AFP) - China announced publicly for the first time Thursday it had mastered the technology to build a neutron bomb. Here is a chronology of its nuclear weapons development:

January 1955: Communist Party chairman Mao Zedong approves development of nuclear weapons programme after presentation by Qian Sanqiang, "the father of China's atom bomb". Formation of Ministry of Nuclear Industry follows.

April 1955: Soviet Union agrees to assist China in research on atomic energy and nuclear physics in first of six nuclear agreements the two nations concluded between 1955 and 1958.

March 1956: Hundreds of Chinese nuclear scientists begin training at Dubna Nuclear Research Institute in Moscow, while nuclear weapons research at Beijing's Institute of Physics and Atomic Energy starts receiving funding and personnel as a priority.

October 15, 1957: Soviet Union agrees to sign New Defence Technology Pact to provide China with sample atomic bomb and technical data on its manufacture. The pact includes delivery of two R-2 missiles.

January 1958: Soviet Union delivers two R-2 missiles and their blueprints.

May 1959: Soviet Union delivers two TU-16 bomber aircraft, one of which is to be assembled in China.

June 20, 1959: Souring relations between the two communist states prompts Soviet Union to inform China it will not provide Beijing with technical details of atomic bombs. China decides to develop its own atomic bombs.

October 16, 1964: China explodes its first atomic bomb at Lop Nor, in the northwestern region of Xinjiang.

June 17, 1967: China tests its first hydrogen (thermonuclear) bomb.

December 27, 1968: China tests a three-megatonne atom bomb at Lop Nor.

September 29, 1969: A further three-megatonne atom bomb explosion.

October 14, 1970: China explodes a three-megatonne hydrogen bomb.

November 17, 1976 : A further hydrogen bomb test.

1980: China conducts last atmostpheric nuclear test. From this time, all further tests are carried out underground.

1988: According to Washington, China goes ahead with a neutron bomb test, but Beijing never confirms report.

July 29, 1996 : China carries out last nuclear test, exploding bomb of just one kilotonne (suggesting China has succeeded in miniaturising warheads).

September 24, 1996: China signs the Comprehensive Test Ban Treaty after a total of 45 tests, 23 atmospheric and 22 underground, according to the US-based Natural Resources Defence Council. By comparison, the United States has conducted 1,030 nuclear weapon tests, not including the two atomic bombs dropped on Hiroshima and Nagasaki in August 1945.

December 1996: By the end of the year Beijing is estimated to have 400 active warheads compared to 10,395 in US, according to the Washington-based Brookings Institution.

November 1998: Allegations surface in the US that China systematically stole US nuclear secrets, including technology for advanced miniature warheads and neutron bombs, during the 1980s and 1990s.

May 25, 1996: Republican Congressman Christopher Cox publishes results of 11-month investigation, saying China stole key weapons secrets and shared them with US enemies. China denies all allegations.

July 15, 1999: China announces publicly it has technology to build a neutron bomb and miniature warheads, publishing details aimed at refuting the Cox report. Experts estimate number of Chinese bombs and warheads at 500.