(Adds Defence Ministry reaction)
TUNIS, March 11 (Reuters) - Tunisia has closed a border crossing with Libya after a clash with smugglers in which a Tunisian soldier was killed, state radio and security sources said on Monday.
The radio said three civilians - two Tunisians and a Libyan - were also wounded in the confrontation between the army and armed smugglers near the Dhiba-Wazn border post on Sunday night.
But a Tunisian Defence Ministry spokesman told state news agency TAP that the soldier was killed in an accident after a car driven by smugglers, without lights, crashed into a military checkpoint. He gave no further details.
Security sources said the crossing, a major trade route, had been closed.
Increased activity by smugglers and Islamist militants near the border with Libya has kept tension high for months.
Trade with Libya is an important source of jobs for Tunisians and any prolonged border closure could provoke unrest in the north African country.
Violent protests took place earlier this year in the Tunisian city of Ben Guerdane after the Ras Jedir crossing with Libya was closed for weeks.
Security is fragile in both countries and border lawlessness increased after the overthrow of Libya's Muammar Gaddafi and Tunisia's Zine al-Abidine Ben Ali in popular revolts in 2011.
Smuggling of commodities such as milk, sugar and barley to Libya has caused shortages and increased prices in Tunisia.
Combating smuggling, unemployment and rising prices will be among the priorities of Tunisian Prime Minister Ali Larayedh's new Islamist-led government, which faces a confidence vote in the National Constituent Assembly on Tuesday. (Reporting By Tarek Amara; Editing by Alistair Lyon and Erica Billingham)