A federal judge ruled Monday that two protest groups cannot use New York City's Central Park as a site for a demonstration days before the Republican National Convention (search).

"This court cannot blind itself to the daunting security concerns facing this city during the Republican National Convention," said U.S. District Court Judge William H. Pauley (search) III.

Pauley said there were serious questions about whether Central Park's Great Lawn can safely accommodate the 75,000 people expected to attend a rally sponsored by the anti-war ANSWER (search) coalition and the National Council of Arab Americans (search).

The written ruling followed arguments Friday before Pauley in which the city maintained it was treating all protesters equally and fairly in denying permits to use the Great Lawn.

Gail Donoghue, special assistant to the city's corporation counsel, had argued that the lawn would be ruined if 75,000 people gathered there for a rally on Saturday.

The two groups had asked Pauley to order the city to issue a permit, saying tens of thousands of people gather on the lawn for musical concerts each year.

United for Peace and Justice also has asked the city for a permit for 250,000 people to rally on the Great Lawn on Sunday. That group filed a lawsuit last week in state Supreme Court in Manhattan, seeking to force the city to let it use the park.