(Reuters) - Enbridge Inc said on Saturday it did not know when it would restart a U.S. oil pipeline that ruptured and leaked crude oil in Wisconsin a day earlier.

The Calgary, Alberta-based pipeline operator said it had not yet determined the cause of the oil spill from the 318,000 barrel-a-day pipeline known as Line 14. The company added it returned Lines 6A and 61 to service early on Saturday, but had not determined when it could restart Line 13.

(Reporting by Jeffrey Jones; Editing by Peter Cooney)