PM Modi was set to make a presentation on the pandemic before MPs of both the Houses.
The Congress and the Shiromani Akali Dal have, for independent reasons, decided to not attend a presentation on Covid that Prime Minister Narendra Modi is scheduled to make today to MPs of both the Houses.
Parliamentary Affairs Minister Prahlad Joshi had on Saturday announced that PM Modi will hold such a session on the pandemic in the Parliament House Annexe.
The Congress today said a discussion on the matter must be held by MPs in the House first.
"If he (PM Modi) wants to give a presentation on Covid, he should give it in the Central Hall separately to MPs and Rajya Sabha members. MPs should be allowed to discuss Covid-related issues in their constituencies," said the Congress's Mallikarjun Kharge, Leader of the Opposition in Rajya Sabha.
Mr Kharge insisted, however, that this wasn't a boycott.
The SAD, meanwhile, based its decision on the long-running farmers' protest over three pieces of Central legislation.
"Today Shiromani Akali Dal will boycott PM Modi's briefing on COVID-19. It will be attended only after he calls a meeting to discuss farm issues," said party chief Sukhbir Singh Badal.
Earlier, several opposition leaders had spoken against the idea of a presentation at a time when Parliament was in session.
Calling the move "highly irregular", CPI(M) General Secretary Sitaram Yechury had said that any address or presentation that the government wants to make must be done inside Parliament.
Derek O'Brien of the Trinamool Congress had tweeted: "MPs do not want fancy PowerPoint presentations on COVID-19 from the PM or this government in some conference room. Parliament is in session. Come to the floor house of the House."