"Shell may have moved an oil rig that ran aground off Alaska last week partly to avoid millions of dollars in taxes, U.S. Rep. Ed Markey said, raising even more questions about the oil company's decision on the timing of the move."

"The letter from the top Democrat on the House of Representatives Natural Resources Committee adds to the already-intense political scrutiny of Royal Dutch Shell's ambitious and troubled Arctic drilling foray last year.

Shell's 30-year-old Kulluk drillship ran aground on New Year's Eve in what were described as "near hurricane" conditions while it was being towed south for the winter.

In a letter to Shell's top U.S. executive, Marvin Odum, Markey said the decision to move the rig "may have been driven, in part, by a desire to avoid...tax liability on the rig.""

Yereth Rosen and Timothy Gardner report for Reuters January 14, 2013. [2]