(In U.S. dollars)

CALGARY, Alberta (Reuters) - U.S. regulators
slapped Enbridge Inc with a $2.4 million fine
Tuesday for a deadly 2007 pipeline explosion in Minnesota as
the company struggled to recover from a rupture three weeks ago
that spewed heavy crude into a Michigan river system.

The U.S. Department of Transportation's pipeline agency
said its investigation into the blast, which killed two workers
in Clearbrook, Minnesota, found the company failed to maintain
and repair its pipeline adequately.

Enbridge also failed to clear the work area of sources of
ignition and did not hire properly trained and qualified
workers, the DOT said.

As part of the ruling, the company must revise its
maintenance and repair procedures, the agency said.

"This department holds pipeline operators accountable for
protecting their own workers as well as the health, welfare and
safety of American communities where they operate," U.S.
Transportation Secretary Ray LaHood said in a statement.

The Calgary-based company and its U.S. affiliate, Enbridge
Energy Partners, are currently awaiting a decision from
the agency on its plan to restart the pipeline that suffered
the leak on July 26 near Marshall, Michigan.

The Pipeline and Hazardous Materials Safety Administration
rejected its last plan on Friday, saying the 190,000 barrel a
day pipeline, called Line 6B, required more extensive testing
before oil flows could resume.

The 2007 blast occurred when the pipeline, the 450,000
barrel a day Line 3 to the U.S. Midwest from Alberta, was at
the end of a repair. On the day after the explosion oil prices
shot up as much as $4 a barrel.

Senator Russ Feingold, a Democrat from Wisconsin, sent
letters on Tuesday to both the PHMSA administrator and
Enbridge's top Canadian and U.S. officials seeking answers on
on what is being done to prevent future spills.

The letter to company officials asked them what steps they
took after the July spill and what measures what they were
doing to ensure the safety of Enbridge's entire pipeline
system.

The letter to PHMSA Administrator Cynthia Quarterman asked
her what steps the agency is taking to ensure Enbridge is
complying with regulations and the degree to which
corrosion-related accidents have occurred in populated areas
versus other areas.

The DOT said it also issued two other orders against
Enbridge, totaling $57,800, for violations at facilities in
Houma, Louisiana, in 2006, and Cushing, Oklahoma, in 2009.
(Reporting by Jeffrey Jones and Timothy Gardner; editing by
Rob Wilson)