The organization said a mob allegedly led by conservative Sunni leaders lynched four Shiite villagers near Cairo last weekend. Deputy Middle East Director Joe Stork said the persecution of Shiites in Egypt is part of a trend that began in the wake of Eygpt's political revolution in 2011.
"The brutal sectarian lynching of four Shia comes after two years of hate speech against the minority religious group, which the Muslim Brotherhood condoned and at times participated in," he said in a statement Thursday from New York.
Human Rights Watch said it was concerned by reports citing the slow response to the attack by area police. The organization called on Egyptian President Mohamed Morsi, a Sunni, to do more to bring the perpetrators to justice.
Amnesty International issued a similar report earlier this week. Both organizations accused Morsi's administration of favoring conservative Sunni ideologies to the detriment of the Shiite community.
Morsi, who hails from the Muslim Brotherhood, issued a statement Monday condemning the weekend attacks but failed to criticize the persecution of Shiites.