WASHINGTON (AFP) - President Barack Obama will raise concerns about nuclear proliferation and resurgent extremism in talks this week with the Pakistani and Afghan leaders, the White House said Monday. We have neglected this region of the world, White House spokesman Robert Gibbs said. The president is concerned about the situation. Wednesdays talks here come as challenges deepen for both President Asif Zardari, whose authority has been crumbling, and Afghan President Hamid Karzai, who is up against a growing Taliban-led insurgency. Gibbs side-stepped questioning about a New York Times report that said US officials are growing more anxious about the security of Pakistans nuclear arsenal, as the Taliban make inroads deep into Pakistan itself. But he said the threat of nuclear proliferation, not just in Pakistan but around the world, is something that the president thinks is of the highest priority. I dont doubt that that will be mentioned. Obama has put nuclear-armed Pakistan at the centre of the fight against Al-Qaeda as he dispatches 4,000 more troops, in addition to an extra 17,000 already committed, to Afghanistan. Obama is to meet at the White House separately with Zardari and Karzai, before hosting a three-way summit to discuss the situation in the region as a whole. Gibbs said the meetings are an opportunity to open up those lines of communication because we want a strong relationship with each of these two countries. Not just the US faces security concerns, but each individual government has security concerns about extremists in the area. This is the beginning of a long process to coordinate our strategy, he said.