WASHINGTON (Reuters) - Election officials in three Pennsylvania counties said they believed no ballots had been wrongly counted as a result of computer malfunctions, despite reports on Tuesday that touch-screen voting machines in the state were switching votes.

Officials in Cumberland, Perry and Butler Counties in Pennsylvania told Reuters that they had no reason to believe the mistakes were affecting voters from one party more than the other, and that voters were catching the mistakes on "review screens" before their ballots were cast.

(Reporting by David Ingram and Julia Harte; editing by Grant McCool)