British oil giant BP said Thursday it had finished sealing the ruptured oil well in the Gulf of Mexico with cement.

A view is seen in the video image captured August 5, 2010 from a BP live feed in the Gulf of Mexico. BP said on Thursday it completed cementing operations at the ruptured oil well in the Gulf of Mexico at 14:15 CDT, as part of the static kill procedure. Monitoring of the well is underway in order to confirm the effectiveness of the procedure. [Xinhua/BP Live Feed]

The company said its engineers finished pumping cement into the leaking well one mile beneath the sea-surface at 2:15 a.m., as part of the so-called "static kill" procedure to plug the well permanently.

BP started pumping cement into the well at 9:15 a.m. Thursday, after drilling mud being pumped into the well earlier succeeded in holding the oil down and the well reached a "static" condition.

All operations were being carried out with the guidance and approval of the National Incident Commander and other government officials, the company said.

U.S. Coast Guard Admiral Thad Allen, who is tasked to handle the oil spill, reportedly gave BP the green light to cement the well Wednesday.

Allen said that the cementing of well "is not the end" of the process, "but it will virtually assure us there's no chance of oil leaking into the environment."

"We will have created a significant milestone and made a major step forward probably by tomorrow (Friday) when the cementing is done," he told reporters.

The cementing is expected to be done by Friday, when the cement sets, he said.

BP said the aim of the "static kill" procedure is to assist with the strategy to kill and isolate the well" and that the procedure will complement the ongoing relief well operation, which is expected to be completed by mid-August.

The "static kill", commenced Tuesday, is the biggest development in BP's 100-day plus spill ordeal since it placed a tight-fitting cap over the blown-out well in mid-July, stopping oil from flowing into the ocean for the first time after a deadly rig blast in late April opened the underwater gusher.

Both Allen and BP officials said relief wells being drilled are the "answer" to permanently sealing the ruptured well. The "static kill" would be followed by a "bottom kill" after a relief well intercepts the underwater gusher.