PRESIDENT Bush will host a six-nation anti-drug summit early next year as a follow-up to the 1990 gathering he attended in Cartagena, Colombia, the White House announced.Although the site of the event has not yet been selected, sources said the meeting would likely be held in the president's adopted home state of Texas. White House press secretary Marlin Fitzwater said Oct. 28 that the summit might be held as soon as February, but that an exact date has not been picked. In addition to Bush, others attending will include the presidents of Bolivia, Colombia, Ecuador, Peru, and Venezuela, Mr. Fitzwater said. He said the summit will build on the "tremendous strides in the drug fight" made as result of the Cartagena meeting, where Bush and the heads of Bolivia, Colombia, and Peru vowed to jointly increase anti-narcotic efforts. Although Bush insists that the United States has begun to win the battle, critics charge that the problem is actually getting worse. A study by the State Department's inspector general estimates that only 1 percent of the drugs smuggled out of Bolivia was being intercepted, and a General Accounting Office report concluded that anti-drug efforts in Peru and Colombia are being mismanaged and are ineffective. Since the 1990 accord, international cocaine seizures have climbed. But so has drug-related violence in the United States.