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. It gave no further details, but security sources said the crossing, a major trade route, was closed after the clash, according to a report of Reuters.