Senegal and the United States on Monday signed a defence accord allowing "the permanent presence" of American soldiers in the west African country, especially to help fight against the terrorist threat.

A key point of the accord will give US troops access to areas in Senegal, such as airports and military installations, in order to respond to security or health needs, according to officials, who did not talk about US bases in the country.

The accord allows for "the permanent presence of American soldiers in Senegal" and aims to "face up to the common difficulties in security" in the region, said Senegalese Foreign Minister Mankeur Ndiaye at the signing alongside the US ambassador to Dakar, James Zumwalt.

After Ebola, which caused more than 11,000 deaths since late 2013 in West Africa, the US diplomat noted that the next crisis could be another epidemic, or a natural disaster calling for a humanitarian response "or a terrorist threat".

The accord sets out the rules for cooperation between the US and Senegalese forces and the conditions for access and for using installations while US soldiers are in Senegal, Zumwalt added.

It also allows for training to enable US and Senegalese forces "to be better prepared to respond together to the risks which threaten our common interests," he said.

Senegal has up to now been spared the deadly jihadist attacks that have hit neighbouring countries, killing 30 people in Burkina Faso's capital in January and causing 19 deaths at an Ivory Coast beach resort in March.

Dakar has beefed up security in many public places including hotels and administration buildings.