Shell idles rigs, takes charge for drilling ban

* Shell takes $56 mln charge in Q2, sees more

* Drillers forced to cut rig rates

* Drill ban to cut Shell production in 2010

* BP declines to comment on possible claims

(Adds detail, background BP comment)

By Tom Bergin

LONDON, July 29 (Reuters) - Royal Dutch Shell Plc (RDSa.L) said it had idled seven rigs and taken a $56 million charge second-quarter charge related to the U.S. deepwater drilling ban and would not rule out reclaiming the cash from BP Plc (BP.L).

Shell, one of the biggest oil producers in the Gulf of Mexico, said it had idled rigs rather than move them elsewhere because the six-month duration of the drilling ban meant it was not profitable to redeploy rigs to other areas.

The Hague-based company said it expected to take a further charge related to the moratorium in the third quarter, although in some cases, rig owners, such as Transocean (RIG.N) and Noble Corp (NE.N), were bearing the lion's share of the losses.

"In some cases we have negotiated a 60-70 percent reduction in the day rates for rigs and services," Chief Financial Officer Simon Henry told reporters on a conference call.

BP declined to say if it would be prepared to compensate Shell, although executives at the London-based oil giant believe it is not liable for damages other companies suffer due to the drilling ban.

U.S. President Barack Obama's government is in a running legal battle with oil companies to stop drilling in the Gulf of Mexico. A six-month moratorium imposed in the wake of the spill has been overturned by a U.S. court but the government is fighting to instate a new one.

Under pressure from the White House, BP has created a $20 billion fund to compensate companies and individuals affected by its oil spill in the Gulf, which was capped a fortnight ago, after spewing up to 60,000 barrels per day of oil into the sea for three months.

However, the fund is not intended to compensate those affected by the moratorium, imposed in the wake of the spill, to allow the government ensure drilling activities were safe.

BP has also created a $100 million fund to compensate oil rig workers who have lost their jobs as a result of the moratorium.

Shell added it would lose almost 3 million barrels of production this year because of the ban.

When asked if the oil spill could have happened to Shell, Chief Executive Peter Voser said on the company was confident in its safety measure but added:

"At the end of the day, you will not be in a position to say it will never happen because accidents do happen".

(Editing by Andrew Callus)