After the results were announced on Thursday, soldiers fired shots in the air in Chad's capital N'Djamena, both in celebration and to deter protesters, AFP journalists reported.

The Chadian media reported there were some deaths caused and numerous injuries by these "joy shots" -- but the government refused to give the number and forbade hospitals to do so, citing "respect for medical confidentiality".

Deby's supporters fired their own guns in the air in celebration near the presidential palace.

At least two teenagers were wounded by falling bullets, according to an AFP journalist.

Chadian soldiers were then deployed in large numbers across several districts of N'Djamena on Friday.

The EU said it was "concerned about the post-election violence," without specifying further.

Elections officials last Thursday declared Deby Itno the winner with 61.03 percent of the vote, compared with 18.53 percent for his rival, Prime Minister Succes Masra.

Masra had earlier claimed victory and accused the junta chief's team of rigging the results, calling on his supporters to "mobilise peacefully".

He then said Sunday he had lodged a request with the Constitutional Council to have the vote annulled.

The regime had long muzzled opposition figures, and Deby's main rival Yaya Dillo was killed in February.

The European Union previously condemned Chad's failure to allow nearly 3,000 civil society members financed by the EU to observe the presidential election.

International human rights groups had said the election would be neither credible nor fair.

Deby was proclaimed transitional president three years ago by his fellow generals after his father, iron-fisted president Idriss Deby Itno, had been killed by rebels after 30 years in power.