Thousands of people including French first lady Carla Bruni-Sarkozy joined in a solemn march in Paris on Sunday to call for Colombian rebels to release former presidential candidate Ingrid Betancourt. French Foreign Minister Bernard Kouchner took part alongside Argentina's visiting President Cristina Kirchner, who has backed France's efforts to secure the release of the 46-year-old, a joint French-Colombian national. Many of the participants wore white t-shirts and armbands, as Betancourt's son Lorenzo Delloye, who has led a high-profile campaign to highlight his mother's plight in France. Similar marches were held in some 20 other French cities. Images and soundbites.