Dylann Roof with a confederate flag and a gun Alleged Dylann Roof website A Democratic congressman has introduced a bill that aims to tighten regulations on gun purchases, in the wake of the church shooting last month in Charleston, South Carolina.

The FBI revealed last week that a clerical error led the alleged Charleston shooter Dylann Roof to legally acquire a firearm.

Rep. James Clyburn's (D-South Carolina) bill aims to end the "default proceed" rule. The rule currently allows federally licensed firearms dealers who have initiated a background check to sell the firearm if they have not been notified by the FBI within three business days whether or not the sale of a firearm to a certain individual would violate federal laws.

On Monday, Reuters reported that when Dylann Roof was arrested in February on a drug offense, a county jail clerk listed the wrong arresting agency in the charging document. The clerk eventually updated the report with the correct information — but only internally.

When the FBI conducted a background check for Roof's pending purchase of the gun thought to be used in the church shooting, they could not find the arrest information in which Roof admitted to drug possession, because it had been transferred from one arresting agency to another without the FBI's knowledge.

Because of this confusion, the FBI did not complete its background check within three business days. Roof was allowed to purchase the gun. FBI Director James Comey said last week that the agency was "sick" at the mistake.

"The Background Check Completion Act will guarantee that no gun is sold by a licensed dealer until a background check is completed," Clyburn said in a statement. "Tragically, the Charleston shooter was allowed to purchase a gun even though the FBI had not completed his background check. This should never be acceptable. My bill is a commonsense fix to our nation’s gun laws, and I call on my colleagues in Congress to move it immediately towards passage."

U.S. Representative James Clyburn (C, right) hugs visiting bishops during a prayer service for Wednesday's shooting victims held at the Morris Brown AME Church in Charleston, South Carolina June 18, 2015. REUTERS/Randall Hill

US Senators Chris Murphy (D-Connecticut) and Richard Blumenthal (D-Connecticut) have also pressed for a similar measure in the wake of the shooting. But they urged the Obama administration to close the loophole through executive action.

"Keeping guns away from criminals is the best thing we can do to fight gun violence. Right now, as we saw with Dylan Roof in Charleston, the government is complicit in arming deadly criminals just because their complicated rap sheets take more than three days to track down," the Connecticut senators said in a joint statement.

"We shouldn't give known criminals the benefit of the doubt when it comes to guns. If law enforcement needs more than three days to ensure they're not giving weapons to dangerous people, Washington must allow them the time to do their jobs. If we refuse to act, we're just biding time until this happens again."

The gun legislation is first of its kind introduced in the wake of the Charleston shooting.