NOUAKCHOTT - Mauritanian police raided the headquarters of two opposition parties, closing one of them amid high tension followed a disputed outcome to presidential elections, sources said Tuesday.

The operation late Monday came after police clashed with opposition supporters angered over the declared victory of ruling party candidate Mohamed Ould Ghazouani, they said.

A former general and long-time ally of outgoing president Mohamed Ould Abdel Aziz, Ghazouani was credited with 52 percent of the ballot, averting the need for a runoff vote.

"Police arrived at the headquarters of candidate Biram (Ould Dah Ould Abeid) and tossed teargas grenades inside, smashing windows and doors, making the place unusable," Abeid's spokesman, Hammada Ould Lehbouss, said on Tuesday.

They also raided the headquarters of opposition candidate Kane Hamidou Baba, the four candidates told a press conference late Monday.

His premises were closed by the authorities, opposition sources said on Tuesday.

The two buildings, located close to each other in the capital Nouakchott, were deserted early Tuesday and rocks used to form roadblocks and burned tires were scattered outside, an AFP reporter saw.

Mauritania's internet connection appeared to be restricted from 1500 local time/GMT on Tuesday with no access to Whatsapp or Facebook, AFP correspondents said.

The government said later Tuesday that it had arrested more than one hundred foreigners, blaming opposition parties for contacts with outside forces seeking to destabilize the country through protests.

"There is a foreign hand behind these events," Interior Minister Ahmedou Ould Abdallah told reporters. He did not give any more details or nationalities, only saying the foreign presence was "linked to certain candidates".

"We have arrested a hundred foreigners whose presence cannot be explained in the context of the election in a country that is not their own," the minister said. -AFP