* No timeline for restarting nearly 1 mln bpd of oil pipes
* Spectra Energy says 280,000 bpd Express-Platte line restarted
June 24 (Reuters) - Major oil Canadian pipelines that move almost 1 million barrels per day (bpd) of Alberta oil sands crude, much of it bound for the United States, remained shut on Monday after a spill on a smaller line was discovered on the weekend, a spokesman for operator Enbridge Inc said.
Enbridge, Canada's largest pipeline company, said on Saturday that 750 barrels of synthetic oil had spilled from the 17-km (11-mile) Line 37, which serves CNOOC Ltd's Long Lake oil sands project in northern Alberta. The rupture was spotted about 70 km (43 miles) southeast of the city of Fort McMurray.
The spill, which may have been caused by the heavy flooding that has also paralyzed the Alberta city of Calgary, headquarters of Canada's oil and gas industry, forced Enbridge to shut two much larger lines as a precaution, threatening a serious disruption in the flow of oil sands crude.
The 345,000 bpd Athabasca pipeline, which carries dilbit blended crude to the Hardisty terminal in Alberta, and the Waupiso line, which can carry up to 600,000 bpd depending on crude viscosity, to Edmonton, Alberta, were both shut. An Enbridge spokesman said on Monday he was unable to give a timetable for resuming flows.
Those are two of the biggest lines that carry crude from the northern production centers around Fort McMurray to the storage and pipeline hub in Hardisty, Alberta, connecting to Enbridge's main export pipeline that runs into the United States.
Traders said the line closure had helped support U.S. crude oil futures on Monday, narrowing the Brent/WTI spread to around $6.50 a barrel, the smallest gap since 2011. Brent crude was down 80 cents at $100.11 a barrel, while U.S. WTI futures slipped 16 cents to $93.53 a barrel.
On Sunday, Enbridge said around 60 workers were at the site of the pipeline leak; the area had been secured and clean-up operations were underway. The leak was contained within Line 37's right of way, at a site with no major roads or human habitation nearby, the company said.
The spill threatens to fan growing criticism of the safety of the North American pipeline network and of expanding production of oil sands crude. A string of incidents in recent years have drawn new attention to oil shipments.
Separately, Spectra Energy said it had restarted its Express-Platte pipeline system on Saturday after shutting the line as a precautionary measure on Friday after heavy flooding caused some communication issues.
The 280,000 bpd Express line carries crude from Hardisty to Casper, Wyoming, while the 164,000 bpd Platte line continues to Wood River, Illinois.