NEW DELHI (Online) Indian Foreign Secretary Ranjan Mathai, who assumed office Monday, said he had been mandated to pursue 'substantive dialogue with Pakistan and underlined that constructive cooperation in the immediate neighbourhood would be one of his key priorities. Mathai, who succeeds Nirupama Rao, Indias next ambassador to the US, said continuity would be the watchword during his tenure and stressed that building cooperative and strong relationships with all the major global players would be amongst his key priorities. The foreign secretary is as much an institution as an individual, Mathai told reporters here after joining his office in South Block in the morning. He stressed the need for a holistic foreign policy that takes care of Indias political and strategic interests, combines the economic and commercial interests of the country, and also keeps in mind the cultural image of the country and the way in which the country portrays itself in the world. Constructive cooperation in the immediate neighbourhood is the main challenge, and I think that will be one of my priority tasks, he said. Mathai also spoke about the need for developing very strong relations with the countries of Africa, Latin America, Central Asia, South East Asia and the Gulf region. I think managing all these would be the major challenge, he said. Days after the foreign ministers of India and Pakistan held talks here, Mathai said he would continue the re-engagement process of restoring trust between the two neighbours.