A stampede occurred in a stadium in the capital Brazzaville on Monday evening, where thousands of young people had come in response to an army recruitment drive.

Congolese government spokesman Thierry Moungala said on Tuesday night that 31 people had been killed and 145 wounded.

He also said that a day of mourning had been decreed for the following day.

On Wednesday, flags were flying at half-mast in government offices and schools were closed across Brazzaville, according to an AFP correspondent. Bars were also closed, although traffic continued to circulate as usual.

Congo-Brazzaville's state prosecutor has opened an investigation into the stampede.

Critics including rights groups and opposition political parties have blamed the government for the stampede, and criticised endemic youth employment.

According to the World Bank, youth unemployment stands at about 42 percent in the country.

The Republic of Congo -- which is also known as Congo-Brazzaville -- is an impoverished country of about 5.7 million people, despite its rich oil and gas reserves.