OTTAWA -- Ottawa's nine-month-old Confederation Line will be out of service all week for maintenance work.

And OC Transpo warns the shut down "may be further extended" while Rideau Transit Group works to improve the $2 billion system.

The O-Train Line 1 was scheduled to be out of service on Sunday for maintenance, with service partially running between uOttawa and Blair stations Monday to Wednesday.

In a memo to Council late Sunday afternoon, Transportation Services General Manager John Manconi said Rideau Transit Group requested to "extend the current full temporary closure of Line 1 until the end of the week."

"We have given approval to extend the closure in order to expedite the required work."

OC Transpo's "R1 replacement bus service" will be available to customers all week along the entire line.

Manconi says OC Transpo will continue to work closely with Rideau Transit Group "as this current closure may be further extended, or additional closures may be required over the summer. The focus remains on improving service reliability for our customers."

Director of transit operations, Troy Charter, did not give a specific timeline for when service on the Confederation Line would resume. In a statement Monday he said that information would be communicated in the coming days.

"A reopening date will be confirmed in the days to come following a detailed assessment of rectification activities as a result of this extended closure," Charter said. "More information will be provided to Council and customers as soon as it is available."

In a statement to CTV News on Monday, transit commission chair councillor Allan Hubley said R1 bus service should accomodate all riders during this time because of lower ridership levels.

"As our ridership is lower than normal, we are taking this opportunity to work with RTM to advance the work required, as part of our Rectification Plan discussed earlier this year," Hubley said. "We know we can accommodate all our ridership with the R1 service until the work is completed, inspected and accepted. By working with RTM in this manner, our expectation of being ready for full service later this summer should be met."

This is the fourth time the Confederation Line has been shut down for maintenance work since the start of May while Rideau Transit Group completes work to improve system performance.

Manconi told Council that last week the RTG was planning to implement updated train control software that was tested during the previous temporary closures. In addition, infrastructure work will continue on the track and the overhead catenary power supply system."