The United States House Homeland Security Committee has claimed al-Qaeda linked group, Al Shahab, had recruited 50 people from Somali American communities to launch the deadly attack on the upscale shopping mall in Kenya on Saturday.
Republican Peter King said 15 to 20 of the Somali Americans recruited by al-Shabab group remained active, Huffington Post reports.
The White House is under pressure to take counter-terrorism action against al Shabab in Somalia following the attack, the report added.
U.S. lawmakers said the attack showed al Qaeda is growing in size and strength, belying the Obama administration's claims that it has grown weaker after the killing of their leader Osama bin Laden.
King also said that he assumes the FBI and local law enforcement were looking at these Somali American communities to make sure no follow-up attacks were planned on the United States.
He likened the incident to the 2011 terrorist attacks in Mumbai, the report added.