In an unusual instance of cross-border cooperation, Pakistani authorities arrested a ranking figure in Afghanistan’s Taliban movement after receiving a tip he had crossed over into Pakistan, officials disclosed Saturday.

Few details were provided about the arrest of Ustad Yasar, a senior aide to Taliban supreme leader Mullah Mohammed Omar. He had been freed by Afghan officials in 2007 in a much criticized prisoner exchange to secure the freedom of a kidnapped Italian journalist.

Pakistani officials said Yasar was picked up in the frontier city of Peshawar, the hub of the nation’s volatile northwest and a growing center of the Islamist insurgency on the Pakistan side of the border. They did not say when the arrest occurred.

Yasar’s arrest was disclosed one day after a meeting in Kabul, the Afghan capital, at which senior Afghan, Pakistani and Western officials discussed ways to better coordinate efforts to fight Islamic insurgents.

Washington

Michelle Obama, two girls in D.C.

Michelle Obama and her two daughters arrived Saturday in Washington, ahead of President-elect Barack Obama who was expected to make the trip today.

The Obamas arrived at their temporary home at the Hay-Adams Hotel, near the White House, on Saturday evening. Aides confirmed their arrival only after the Obamas checked into the hotel, and declined to release any details. They had no public schedule.

The Obamas moved early so their daughters – 7-year-old Sasha and 10-year-old Malia – could start classes on Monday at the private Sidwell Friends School, an aide said.

The Obamas are staying at the storied Hay-Adams because Blair House, the government’s official guest residence, was booked solidly through Jan. 15, the Bush administration said. Blair House is located across Pennsylvania Avenue from the White House and has previously housed presidents-elect before taking the oath of office. The Obamas will relocate there on Jan. 15 and stay until the inauguration on Jan. 20.