Gunmen shot dead a Nigerian army general as he was travelling by car on a major road from the capital, Abuja, the army said on Friday, in the first such fatal gun attack on a senior serving military officer.

Armed robberies and kidnappings for ransom, particularly in the northwest, have become so frequent that many are afraid to travel by road. Growing nationwide lawlessness led legislators in April to call on the president to declare a state of emergency.

Major General Hassan Ahmed was killed when gunmen attacked his vehicle along the Lokoja-Abuja road on Thursday, army spokesman Brigadier General Onyema Nwachukwu said in a statement. Lokoja, 200 km (124 miles) south of Abuja, is the capital of Kogi state.

Nwachukwu did not say who was travelling with Ahmed, or how far outside of Abuja he was, but local media said the deceased general was with his driver and a relative.

Ahmed was a director at army headquarters, and had earlier served as the army's Provost Marshal. While two retired generals were shot dead last year in attacks as they travelled by road, no serving general had previously been killed in this manner.

The insecurity in northwestern Nigeria is joined by Islamist insurgencies in the northeast that the United Nations says have left 350,000 people dead over 12 years.

In the middle of the country, conflicts between nomadic cattle herders and farmers have killed thousands and displaced half a million over the past decade, according to French medical charity Medecins Sans Frontieres. In the southeast, a recent spate of attacks on police has triggered fears of a return to war and state-sanctioned violence.