Sandinista supporters decked the streets of Managua with red-and-black flags in preparation for a massive rally Wednesday marking 10 years since an armed uprising overthrew dictator Anastasio Somoza.

Leaders of the governing Sandinista National Liberation Front scheduled the Wednesday morning rally in the same downtown square - renamed Revolution Square - where they celebrated their triumphant march into Managua July 19, 1979, after a bloody civil war that ended a 50-year-old Somoza family dynasty.President Daniel Ortega was scheduled to make a speech at Wednesday's rally, but he told an official radio station Tuesday not to expect major announcements - apparently confirming what diplomats described as a rather low-key anniversary celebration darkened by the magnitude of the country's economic and political crisis.

"Of course the Sandinistas are celebrating, but they are also aware that the economy is on the verge of collapse," said a European diplomat.

Hundreds of militants of the 37,000-strong Sandinista Front were busy throughout Managua Tuesday, hanging banners with the slogan: "We've notched up 10 and we're still going strong," painting red-and-black hearts on walls with the legend, "There's never been so much patriotism in one heart," and bedecking the city with bunting in the red-and-black Sandinista colors.

Security also was tightened around the capital, with hundreds of police officers posted on major roads and checking cars for hidden explosives at sensitive spots like the airport and government buildings. The government announced all flights in and out of Nicaragua would be canceled Wednesday to mark the national holiday.

Pro-government newspapers predicted 300,000 Nicaraguans would turn out for the anniversary rally, but diplomats speculated the crowd would not surpass 100,000.

The anniversary marks the day in 1979 when the top Sandinista leadership - including Ortega and eight colleagues on the Sandinista Front National Directorate - marched into Managua after a broad-based uprising succeeded in ousting Somoza, a widely hated strongman.

At the time, the Sandinista National Liberation Front was a ragtag guerrilla army of about 5,000 fighters and civilian supporters, but the front moved quickly to consolidate its leadership position and gain control of Nicaragua's government.