A security source said armed men had attacked the interior of the presidential compound but authorities made no immediate comment.

All roads leading to the presidency have been blocked and tanks could be seen on the streets of the capital, according to an AFP reporter on the scene.

The gunfire erupted less than two weeks after the landlocked country in Africa's northern half held a contested general election.

The government hailed it as a key step towards ending military rule, but it was marked by low turnout and opposition allegations of fraud.

The election had taken place against a backdrop of recurring attacks by the jihadist group Boko Haram in the Lake Chad region, the ending of a military accord with former colonial master France, and accusations that Chad was interfering in the conflict ravaging neighbouring Sudan.

Several hours earlier on Tuesday, China's foreign minister Wang Li met with President Mahamat Idriss Deby Itno and other senior officials.

The former French colony hosted France's last military bases in the region known as the Sahel, but at the end of November it ended the defence and security agreements with Paris.

Around a thousand French military personnel were stationed there, and are in the process of being withdrawn.

France is now reconfiguring its military presence in Africa after being driven out of three Sahelian countries governed by juntas hostile to Paris -- Mali, Burkina Faso and Niger.

Senegal and the Ivory Coast have also asked France to leave military bases on their territory.