TEHRAN (Reuters) - Iran called the deployment of foreign troops in Bahrain unacceptable on Tuesday and warned Saudi Arabia and its ally Washington of "dangerous consequences" for intervening in the island nation's political crisis.

About 1,000 Saudi soldiers entered Bahrain on Monday as part of an effort by the six-nation Gulf Cooperation Council (GCC) to help the government cope with protests by members of the Shi'ite majority.

The move has alarmed Iran, the main Shi'ite power in the Gulf where most ruling families are Sunni Arabs. Analysts say Saudi Arabia's action might increase tensions with Iran -- both major oil exporters -- to dangerous levels.

"The presence of foreign forces and interference in Bahrain's internal affairs is unacceptable and will further complicate the issue," Foreign Ministry spokesman Ramin Mehmanparast said at his weekly news conference.

Tehran said Washington was responsible for pushing its ally and oil supplier Saudi Arabia into getting involved in Bahrain, a small but important U.S. ally which is home to the U.S. Navy's Fifth Fleet.

The Pentagon has said it was not given any advance notice that Saudi or other regional forces would deploy to Bahrain.

Tehran summoned the ambassadors of Saudi Arabia and of Switzerland, which represents U.S. interests in the absence of direct diplomatic relations.

"Iran considers the United States as responsible for the dangerous consequences of such an illegal move," the ISNA news agency quoted the Foreign Ministry as saying.

The arrival of the Saudi forces came after mostly Shi'ite demonstrators overwhelmed Bahraini police on Sunday and blocked the highway to the main financial district in the most violent confrontations since troops killed seven protesters last month.

Bahrain's Shi'ites have complained of discrimination by the Sunni royal family and intervention in Bahrain by Gulf Arab troops is highly sensitive.

Iran's parliament also condemned the Saudi deployment.

"The Saudi rulers' sending of troops to Bahrain will not only bring a halt to the Bahraini people's movement, but also will bring dangerous consequences for the illegitimate Saudi ruling regime," said a declaration signed by 257 lawmakers, carried by the official IRNA news agency.

Iran, which has crushed opposition protests at home, has welcomed uprisings across the Arab Middle East as an "Islamic awakening" against despotic rulers.

Accusations abound of Iranian backing for activists among the Shi'ite majority in Bahrain, a charge Tehran has denied.

Mehmanparast dismissed as irrelevant a question about the possibility of Iran sending forces to Bahrain.

"Basically, we do not regard the presence and interference of other countries, especially the countries of the Persian Gulf region in the Bahrain issue, as correct," he said.

"Such interference and increasing suppression and violent confrontation is not the solution to the legitimate demands of the people."