Bettaccini TITJUR Opinion of Mr Advocate General Jacobs delivered on 14 April 1994. # Lio Bettaccini v Fonds National de Retraite des Ouvriers Mineurs. # Reference for a preliminary ruling: Tribunal du travail de Mons - Belgium. # Social security for migrant workers - Increase in invalidity pension - Application of national rules against overlapping of benefits. # Case C-301/93.