LAGOS, Nigeria (Reuters) - The Nigerian government ordered senior civil servants to return to work as a general strike over sharp increases in gasoline prices spread to the country's mainstay oil industry Friday.
An Information Ministry statement quoting civil service head Abu Obe, said senior civil servants were by law not permitted to join in any industrial action.
The statement came after members of the white collar oil workers' union, PENGASSAN, joined the strike.
Members of this union include senior civil servants from the department of petroleum resources and state-owned Nigerian National Petroleum Corporation (NNPC), the backbone of the country's economy.
These members, among other tasks, process vital oil export documents. Oil firms have in the past used management staff to fill in for striking PENGASSAN workers.
The statement also said Nigeria's international and domestic airports were operating normally and air traffic controllers had not joined the strike.
Airline officials confirmed that at least two international flights operated at Lagos airport Friday -- a Kenya Airways flight and a British Airways flight that had been diverted to neighboring Ghana Thursday.
One domestic airline company said it had begun offering ''skeleton services,'' but the strike looked certain to hit supplies of aviation fuel and further compound problems for the air services.
The strike, ordered by the umbrella Nigerian Labor Congress (NLC), entered its second day Friday, threatening to be the biggest disruption in Africa's top oil exporter since military rule ended one year ago.
Oil tanker drivers joined the action Friday when they stopped loading petroleum products from state-run NNPC fuel depots. The move triggered a severe shortage of petroleum products in many cities.
Royal Dutch/Shell, Nigeria's biggest oil producer, said its junior workers had also stopped work, but that oil loadings at its Bonny and Forcados export terminals were unaffected yet.
Two other major multinationals involved in producing Nigeria's 2 million barrels per day oil output -- TotalFina Elf and Chevron -- said their junior workers were also on strike. But they too said export loadings at their terminals had not been disrupted.
The oil sector had been unaffected on the first day of the strike.
The NLC Thursday turned down an offer by President Olusegun Obasanjo to cut the rise in the price of gasoline to 25 naira per liter, about 91.2 U.S. cents per gallon, from the 30 naira per liter, or $1.10 per gallon, announced last week.
NLC president Adams Oshiomhole told reporters his group rejected anything less than a complete return of all products to their original prices. Gasoline previously sold for 20 maira per liter, or 72 U.S. cents per gallon.
The price increases are part of Obasanjo's economic policy of deregulation and ending subsidies as demanded by the International Monetary Fund as a condition for a $1 billion standby loan it has agreed to make to Nigeria.
The price hikes are unpopular in Africa's biggest oil exporter, where citizens see cheap gasoline as the only tangible benefit from governments unable to deliver amenities such as water and electricity.