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LAGOS, Feb 8 (Reuters) - Nigeria's white collar oil workers' union PENGASSAN will not begin strike action on Monday over insecurity in the Niger Delta as originally threatened because it is still in talks, the body's secretary general said.

"Our ultimatum to the government ends tomorrow but we will not begin our strike. We are still meeting with our sister union NUPENG ... to agree a date to begin the strike," PENGASSAN Secretary-General Bayo Olowoshile told Reuters.

PENGASSAN warned last Tuesday it was planning indefinite strike action from Monday unless the government took immediate steps to improve security in the Niger Delta, the country's oil heartland which has been plagued by violent crime.

The strike threat came less than a week after gunmen killed an 11-year old Nigerian girl and abducted her 9-year old brother as they walked to school in the southern oil city of Port Harcourt. Their father works for Royal Dutch Shell <RDSa.L>.

The boy has since been released, as have the wife of a former oil minister and a local employee of Italian energy firm Agip <ENI.MI>, all kidnapped in recent weeks.

PENGASSAN has not said what measures the government or security forces must put in place before it lifts its threat. Similar threats made by the union over insecurity in the past were withdrawn after talks with the authorities and oil firms.

The Movement for the Emancipation of the Niger Delta (MEND), the main militant group in the region, called off a five-month-old ceasefire just over a week ago.

The group, which is still holding two British oil workers kidnapped last September, said on Saturday its fighters had attacked the Utorogu gas plant in Delta state operated by Shell.

A spokesman for Shell in Nigeria confirmed the attack and said one employee of its SPDC joint venture and two contractors had been injured but were in a stable condition.

There was no damage to the facility itself. (For full Reuters Africa coverage and to have your say on the top issues, visit: http://af.reuters.com/ ) (Reporting by Tume Ahemba; Writing by Nick Tattersall; Editing by Mike Nesbit)

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