LONDON — Construction of the Olympic Stadium for the 2012 London Games began Thursday with a groundbreaking ceremony attended by British Prime Minister Gordon Brown.

The work to create the permanent foundation for the stadium in the Olympic Park in the East End of London coincided with the final day of a three-day visit by International Olympic Committee officials monitoring preparations for the games.

Work on the 80,0000-seat showpiece venue began three months ahead of schedule.

"The early start to building work on the Olympic Park site is good news, taking us another step closer to 2012 and the regeneration of one of the country's most deprived areas," Brown said. "I have no doubt that the construction of the new permanent venues, infrastructure and transport links within the largest new urban park to be created in Europe for 150 years will be a catalyst for lasting social and economic change in east London."

The $980 million Olympic Stadium will include permanent seating for 25,000 spectators, with the remaining 55,000 seats in a temporary structure at the top. The stadium covers 40 acres.

After the Olympics, the stadium will be converted to a 25,000-seat arena for track and field.

Preparatory work on the stadium has involved lowering ground levels by 30 feet to create the area for the track and permanent lower tiers of seating.

"Over the next year the Olympic Stadium structure will begin to emerge from the ground," Olympic Delivery Authority chairman John Armitt said. "It is great news that we can make an early start but this is a project with an immovable deadline so we know there are big challenges ahead."

The first phase of construction involves reinforcing the foundations of the stadium with 4,000 concrete columns. By the end of the year, floor slabs will be laid for the base of the stadium bowl and the lower tier structures and the columns that support the pedestrian concourse level will be built.

Early in 2009, the erection of the steel structures that will support the roof will begin. The stadium is scheduled to be completed in 2011.

"There is still a lot of work to be done and many challenges to come," Olympics Minister Tessa Jowell said. "But I am delighted with what has been achieved so far and, as we prepare for Beijing, it is immensely reassuring to know that preparations for our games are on time and on track."