ISLAMABAD, Pakistan — After years of living in the open in Pakistan despite a $10 million American bounty, the militant leader accused of orchestrating the 2008 Mumbai attacks, Hafiz Muhammad Saeed, was placed under house arrest in Lahore on Monday, Pakistani officials said.

The move against Mr. Saeed, the founder of the banned militant group Lashkar-e-Taiba, came amid a reported new round of pressure by the United States to arrest Mr. Saeed and to ban Jamaat-ud-Dawa, the charity he leads, which has been accused by American officials of being a front for militants. The News, a Pakistani English-language newspaper, reported on Monday that American officials in the waning days of the Obama administration had threatened sanctions or other penalties if action was not taken.

On Monday, Chaudhry Nisar Ali Khan, the Pakistani interior minister, announced that action against Jamaat-ud-Dawa was being discussed and that a decision would be announced on Tuesday. Hours later, police officers arrived at the group’s headquarters in Lahore and placed Mr. Saeed under house arrest. Party banners and flags were removed from the offices.

This is not the first time, however, that Mr. Saeed has been put under house arrest, and he has repeatedly avoided long-term detention or serious legal charges. He was placed under detention at least twice after the 2008 attacks in Mumbai, which killed at least 166 people. India claimed almost immediately then that Mr. Saeed was the mastermind of the terrorist attacks.