US POLICE HAVE arrested one man in Philadelphia, Pennsylvania, over what US media has said was a plan to attack a count centre. 

Shortly after 10pm (3am Irish time), a man was detained outside the Philadelphia Convention Centre where vote counting is ongoing. 

Local television channel 6ABC Action News reports that police received a tip that an armed group had driven from Virginia to Philadelphia, a drive of several hours, to carry out some kind of attack at the count centre. 

The group is possibly a family, the site reports. 

Police have recovered a weapon and seized the Hummer vehicle that the group travelled in. No injuries have been reported.

Pennsylvania is a battleground state which is yet to declare a winner in the presidential election. 

Since election day, US president Donald Trump has fired off tweets calling for ballot counting to be stopped, and contended without proof there has been voter fraud.

But his tweets have been masked by Twitter with notices telling people the claims are misleading.

On Thursday Facebook shut down pro-Trump group “Stop the Steal” that was organising protests against vote-counting.

This is a breaking story. More to follow.