"We have built a large tent to protest against the U.S. anti-missile radar base in Prague's Wenceslas Square for one month," Landergott said.
Since the tent was erected on June 17, another 15,000 people have signed on the petition, organized by the No to Bases, she added.
"Our goal is to show our will of opposition of the base and seek more support from public," Landergott said.
The Czech Republic signed early this month a treaty with the United States on the stationing of a radar base at the Brdy military district, some 90 km southwest of Prague, within the U.S. anti-missile shield. The treaty is yet to be ratified by parliament.
The United States plans to build the radar base in the Czech Republic along with an interceptor missile base in neighboring Poland.
A recent opinion poll showed that up to 70 percent of Czech citizens oppose the project.
Russia is also strongly opposed to the missile defense system plan in eastern Europe, saying the plan poses a threat to its strategic interests.
Landergott said that the opponents will continue their protest in a bid to prevent the project from being ratified by Czech parliament.
About 50 volunteers take their turns in the tent from June 17, each of them staying there for nine hours in daylight and six hours at night.
