Authorities Monday imposed "urgent measures" to quell continuing unrest by workers and students demanding political and economic reform in the southern republic of Montenegro.

The measures ordered by the state leadership of Montenegro included increasing the number of police patrols in the streets of the capital of Titograd, a police official said by telephone from the city.President Raif Dizdarevic appealed Sunday for an end to the demonstrations that have shaken his ethnically diverse nation, warning that the government would not allow the country to be torn apart by civil strife.

The president said the tense situation might lead to "extraordinary conditions," an apparent allusion to a possible crackdown on mass protests similar to police strongarm tactics in Titograd Saturday.

The government of Montenegro, one of Yugoslavia's six republics, introduced the unspecified measures Monday in Titograd "to prevent an extraordinary situation because the security situation rapidly turned for the worse."

Montenegro state presidency member Blazo Orlandic said these "urgent measures are of limited character and are directed exclusively against those who misuse the justified dissatisfaction of the workers and citizens."

The government statement said militant groups have begun "threatening to virtually suspend institutions of the legal political system and endanger personal security of the citizens and their property."

Police clashed Saturday with protesters in Titograd and the town of Niksic, 37 miles north of Titograd, leaving 13 people injured.

Husnija Redzepagic, a senior official in the Montenegro Secretariat for the Interior said Monday police in Niksic arrested another 12 people Sunday during a demonstration to demand the resignation of Montenegro leaders. A police official in Titograd told UPI, "It is calm here (today) and citizens of Titograd live a normal life."

But about 2,000 workers continued a strike at a construction equipment factory Monday.

In Niksic, workers demonstrated Monday at a bauxite mine and at the Piva hydro-electric power station. Several hundred high school and university students and professors demonstrated in front of the Niksic town hall.

Dizdarevic said in his speech Sunday that authorities "will do everything the Constitution and law permit so as to protect the public order and peace, the security of citizens and their property and the constitutional order."

Dizdarevic, 62, conceded in the nationwide broadcast that Yugoslavia is in a grave economic and political crisis and said he understands that people are deeply worried and dissatisfied. But he said government reforms aimed at introducing free-market rules in the Yugoslav system of worker self-management are the only way out of the crisis.