Violence since 2006 has cut oil production in Nigeria by a fifth
Oil workers in Nigeria's Niger Delta have gone on strike to protest at the lack of security in the restive oil-producing region.
Staff members from oil company Total went on strike even after their national union executive said it would delay industrial action.
Last week the 11-year-old daughter of an oil worker was killed as she tried to prevent her brother being kidnapped.
It is unclear if the walkout will affect output or spread to other firms.
Workers in the Total chapter of Petroleum and Natural Gas Senior Staff Association of Nigeria (Pengassan) picketed the company office in Port Harcourt.
Pengassan is the white-collar management staff union.
Its secretary general, Bayo Olowoshile, had told reporters on Sunday they were suspending their planned strike as talks with the blue-collar workers' National Union of Petroleum and Natural Gas Workers (Nupeng) were continuing.
Kidnappings of employees and their families has increased over the last few months.
Over the weekend the Movement for the Emancipation of the Niger Delta (Mend) claimed to have attacked a gas plant in Delta State.
The military said it had repelled the attack in the early hours of Saturday morning and killed three militants.
The wife of Edmund Daukoru, the former oil minister, was released on Friday after being kidnapped by unidentified gunmen last week.
Mend claimed not to have had anything to do with the abduction, but in a press release to journalists, claimed Gladys Daukoru's family had paid a $2.5m (£1.69m) ransom for her safe return.
They said the gang had threatened to "rape her every day" unless they were paid.
Militants say they are fighting for a better share of the oil wealth, but armed gangs make money from kidnapping, extortion and oil theft.
Violence since 2006 has cut oil production in the world's eighth largest exporter by around a fifth.