* The Babcock & Wilcox Co., Jacobs Engineering on ban list
* BAE Systems, Finmeccanica, FMC Corp off ban list
* Siemens off observation list
OSLO, Jan 11 (Reuters) - Norway banned its $700 billion oil fund from investing in several companies involved in nuclear weapon making and lifted investment bans on several others, the Finance Ministry said on Friday.
The fund, the world's biggest with around 1 percent of all global shares, can no longer invest in The Babcock & Wilcox Co. and Jacobs Engineering Group Plc because they are involved in the production of nuclear weapons, the Ministry said in a statement.
"The Babcock & Wilcox Co. operates and has operational responsibility for state-owned plants that produce fissionable material for nuclear warheads, and maintains and upgrades such warheads," it said.
"Jacobs Engineering Group Inc. has stated that it is now participating in a joint venture company engaged in the development, production, testing and maintenance of nuclear warheads.
Neither company was immediately available to comment.
The ministry, however, lifted the investment ban on several companies, including BAE Systems Plc, Finmeccanica S.p.A, and FMC Corporation.
"BAE Systems Plc. and Finmeccanica S.p.A were excluded due to their involvement in the production of nuclear weapons," the government said.
"The companies have informed the Council on Ethics that the production of the ASMP-A nuclear missile by their joint venture company MBDA has ceased."
FMC was earlier banned for its involvement in the purchase of phosphate from Western Sahara, which it no longer does.
The government also took Germany's Siemens AG off its list of companies that could be excluded from investment in the future after the company demonstrated zero tolerance to corruption.