US Cash Crude-Mars eases after strengthening in previous session

April 9 (Reuters) - Mars Sour eased on Wednesday after doubling in the previous session as a key pipeline shipping Canadian crude to feed U.S. refineries went offline.

The Keystone oil pipeline from Canada to the United States remained shut on Wednesday following an oil spill near Fort Ransom, North Dakota, and "return to service" plans are being evaluated, its operator South Bow SOBO.TO said.

Some U.S. refiners, especially in the Midwest, rely heavily on the type of oil produced in Canada and delivered by Keystone.

U.S. crude oil stockpiles rose by 2.6 million barrels to 442.3 million barrels last week as imports increased and exports fell to their lowest since January, the Energy Information Administration said.

* Light Louisiana Sweet WTC-LLS for May delivery rose 5 cents to a midpoint of a $2.50 premium and was seen bid and offered between a $2.40 and $2.60 a barrel premium to U.S. crude futures CLc1

* Mars Sour WTC-MRS eased 5 cents to a midpoint of a 95-cent premium and was seen bid and offered between a 75-cent and $1.15 a barrel premium to U.S. crude futures CLc1

* WTI Midland WTC-WTM eased 15 cents to a midpoint of a 90-cent premium and was seen bid and offered between a 70-cent and $1.10 a barrel premium to U.S. crude futures CLc1

* West Texas Sour WTC-WTS eased 5 cents to a midpoint of a 10-cent premium and was seen bid and offered between parity and a 20-cent a barrel premium to U.S. crude futures CLc1

* WTI at East Houston WTC-MEH, also known as MEH, traded between a $1.00 and $1.50 a barrel premium to U.S. crude futures CLc1

* ICE Brent June futures LCOc1 rose $2.66 to settle at $65.48 a barrel on Wednesday

* WTI May crude CLc1 futures remained unchanged at $62.35 a barrel on Wednesday

* The Brent/WTI spread WTCLc1-LCOc1 narrowed 8 cents to last trade at minus $3.64, after hitting a high of minus $3.57 and a low of minus $3.87