Facing an increase in officers leaving the force, D.C. Police Chief Charles H. Ramsey has issued a restriction on how officers can retire or resign, saying he was worried about short staffing as his department battles a spike in juvenile violence and the threat of terrorism.

In a memo issued last week, police officials announced that Ramsey will no longer grant waivers of departmental regulations that require officers to give 60 days' notice before retiring and 30 days' notice before resigning. Ramsey said he had generally waived those requirements in the past.

Union officials reacted angrily to the move yesterday, saying the decision was unfair and would further erode low morale among the rank and file.

"This is clear evidence of problems with the police department," said Sgt. Gregory I. Greene, chairman of the D.C. police labor committee in Fraternal Order of Police Lodge 1. "A lot of officers are leaving."

Ramsey acknowledged that more officers have left the force in recent months than usual; 198 have departed this year, or about 28 a month. Those officers retired, resigned or were fired, Ramsey said.

That number is higher than the average in past years of 18 to 20 officers a month, Ramsey said.

Ramsey ordered the restrictions before the department went to higher alert status Sunday in light of terrorist research on the World Bank and International Monetary Fund headquarters downtown as potential terrorism sites.

"That says to me I made the right decision," Ramsey said. "We need all hands on deck. . . . We have a lot of challenges facing our city."