The offices of Western oil companies in Nigeria were closed, along with most other businesses and government offices, but oil production and shipments remained uninterrupted, company officials said.
One Western executive was quoted as saying: "All our offices are locked up, but there has been no interference in our operations yet."
Unions ordered workers to go on "total strike", but leaders of the oil unions said it would take time to shut the industry down.
Oil companies use non-unionised staff to maintain essential operations, but some union members are required to sign off on exports and this is where unions hope to put pressure.
Streets in the main cities were deserted, partly due to an earlier five-day-old strike by road tanker drivers which has left most of the country without fuel.
Some international and domestic flights had been cancelled because of a shortage of jet fuel.
Unionists barricaded streets in Port Harcourt, Nigeria's southern oil capital, and ejected workers who turned up for work at government offices in the capital Abuja.
Yar Adua agreed to reverse the tax increase and to implement a public sector pay rise as demanded by the unions, but talks broke down over the fuel price.
Unions rejected the government's offer to reduce pump prices by 4 cents a litre, saying only a full reversal of its 10-naira increase would stop the strike.
The majority of Nigerians live below the poverty line and fuel subsidies are seen as one of the few benefits they receive from a government that has failed to deliver power, water, healthcare or schools.
In London, oil futures, which have been supported by fears of a disruption from Nigeria, fell by 50 cents to $71.34 a barrel.