Nigerian regulators have told parliament that Royal Dutch Shell, the Netherlands-based oil and gas company, should be fined $5bn for environmental damage caused by an oil spill at its offshore Bonga field in December.  Shell has shunned the requests, saying there was no legal basis for the proposed fine.  The country's National Oil Spill Detection and Response Agency (NOSDRA) told a parliament  Monday that last year's spill was about 40,000 barrels.