Democratic Republic of Congo protest
The arrest occurred amid growing tensions over next year's presidential election. In January, at least 40 demonstrators were killed during violent protest against a proposed electoral law, seen by some as a way to delay the election. (Reuters)

The Democratic Republic of Congo has released US diplomat Kevin Sturr, who was arrested along with African journalists and pro-democracy activists on grounds they were posing a threat to the government.

The arrest occurred on 15 March following a conference in the capital Kinshasa that promoted the participation of youths in politics, AP reported.

Those arrested were suspected of being a threat to national security, according to Lambert Mende, the government spokesman. Referring to Sturr, he said the conference was "no place for a diplomat".

"He was returned to the embassy late last night," Mende continued and added the journalists were also released but the activists are still being held.

"There are the three Senegalese and the Burkinabé and their Congolese accomplices who continue to be questioned. Each will have his fate... Either they will be released or put at the disposition of the public prosecutor."

The incident occurred amid growing tensions in Congo over fears incumbent President Joseph Kabila is seeking to remain in power after his term ends in 2016. Kabila assumed office in 2001 and is constitutionally barred from seeking a further term in office.

In January 2014, dozens of Congolese people took to the streets to protest against a draft electoral law requiring a census to take place before a presidential election. The bill was seen by critics as a way to delay polls.

After clashes resulted in the death of at least 40 protesters, Congo's parliament voted in favour of the bill but agreed to remove the provision that made the election contingent on the census.