Exxon crews repaired a damaged section of the pipeline in Missouri last week after about 42 gallons of oil spilled.
Patricia Klinger, a spokeswoman for the Pipeline and Hazardous Materials Safety Administration, told the Log Cabin Democrat, a Conway, Ark., newspaper, inspectors were looking at all 850 miles of the pipeline after a March rupture of the pipeline spilled about 5,000 barrels of oil in the Mayflower, Ark., neighborhood.
That means Exxon won't restart the entire pipeline until a full inspection is conducted.
"We will not restart the pipeline until both the relevant government authorities and we are convinced it is safe to do so," Exxon spokesman Michael Kontos told the newspaper.
The pipeline was carrying a diluted form of so-called oil sands from Canada at the time of the March incident in Arkansas. Authorities say air and water quality is within safe limits and Exxon has moved to a long-term remediation phase to clean a marshland soiled by the spill.