Klete Keller, a former Olympic swimmer who won two gold medals for the US, has pleaded guilty to a felony charge related to his participation in the January 6 riot at the US Capitol.

Keller admitted to obstructing an official proceeding after prosecutors agreed to drop six other criminal charges they brought against him in February.

US District Judge Richard Leon in the District of Columbia accepted Keller’s guilty plea at a court hearing on Wednesday (local time). Judge Leon will sentence Keller for his role in the violence led by supporters of former president Donald Trump at another hearing that has yet to be scheduled.

The charge has a recommended sentence of between 21 and 27 months in prison, but Judge Leon is not bound by that range.

Keller is a five-time Olympic medallist who held off Australian great Ian Thorpe on the anchor leg of the 4×200-metre freestyle relay at the 2004 Athens Games to win gold for the US.

More than 600 people have been charged with taking part in the January 6 violence, which followed a speech by Mr Trump at a nearby rally repeating his false claims that his election loss to Democrat Joe Biden was the result of widespread fraud.

Keller, a Colorado resident, wore a Team USA jacket when he entered the Capitol.

According to prosecutors, Keller was in the Capitol for nearly an hour, at one point yelling “F— Nancy Pelosi!” and “F— Chuck Schumer!” before others began pushing forward toward law enforcement officers.

Ms Pelosi and Mr Schumer are the Democratic Party’s congressional leaders.

-AAP