his action is not considered as mutual legal assistance in the strict sense of the term, given that it occurs spontaneously. Statutory basis: - Convention implementing the Schengen Agreement of 14th June 1985 on the gradual abolition of checks at common borders (art. 41), as approved by statute of 3rd July 1992, and its Protocol of 24th June 1997, approved by statute of 8th April 1999, and amended and completed by Council Decision 2003/725/JHA of 2nd October 2003; - Treaty between the Kingdom of Belgium, the Kingdom of the Netherlands and the Grand Duchy of Luxembourg concerning cross-border police intervention (art. 18), approved by statute of 21st December 2004; - Convention drawn up, on the basis of Article K3 of the Treaty on European Union, on mutual assistance and cooperation between customs administrations, done at Brussels on 18th December 1977 (art. 20), approved by statute of 6th July 2001.