Pound hits 31-year low as leave side takes lead in EU vote

A dealer watches monitors at the foreign exchange dealing room in Seoul, South Korea, Friday, June 24, 2016. Asian stock markets were volatile on Friday with Tokyo stocks and U.S. futures plunging as early vote results on whether Britain should stay in the European Union showed a tight race. (AP Photo/Lee Jin-man) (The Associated Press)

A currency trader rubs his eyes at the foreign exchange dealing room in Seoul, South Korea, Friday, June 24, 2016. Asian stock markets were volatile on Friday with Tokyo stocks and U.S. futures plunging as early vote results on whether Britain should stay in the European Union showed a tight race. (AP Photo/Lee Jin-man) (The Associated Press)

Currency traders talk near screens showing foreign exchange rates between British pound/the U.S. dollar and euro/the U.S. dollar at a foreign exchange dealing room in Seoul, South Korea, Friday, June 24, 2016. Asian stock markets were volatile on Friday with Tokyo stocks and U.S. futures plunging as early vote results on whether Britain should stay in the European Union showed a tight race. (AP Photo/Lee Jin-man) (The Associated Press)

The pound slumped to its lowest in more than three decades on Friday as results on Britain's vote on European Union membership give the "leave" side a small but growing lead.

The currency tumbled to as low as $1.3460 on Friday, which was its lowest level in 31 years.

It fell about 10 percent from the 2016 high of $1.50 hit just hours earlier.

Uncertainty over the vote's outcome has kept world currency markets on edge.

The yen, meanwhile, strengthened as investors sought safety in the currency, which is considered a haven.