DUBAI — More than 1,000 Saudi troops, part of the Gulf countries' Peninsula Shield Force, have entered Bahrain where anti-regime protests have raged for a month, a Saudi official said Monday.

The troops entered the strategic Gulf kingdom on Sunday, the official told AFP, requesting anonymity.

The intervention came "after repeated calls by the (Bahraini) government for dialogue, which went unanswered" by the opposition, the official said.

According to the regulations of the Gulf Cooperation Council, "any Gulf force entering a member state becomes under the command of the government," the official added.

The Bahraini government has not confirmed the presence of Saudi troops in the archipelago, which is home to the US Fifth Fleet.

Opposition protesters are demanding far-reaching democratic reform in the mainly Shiite country which has been ruled by a Sunni Muslim dynasty for more than 200 years.

The king has offered dialogue and a new, empowered parliament and other reforms but the opposition has refused to sit down to talks until the government resigns.

The Saudi intervention comes two days after US Defence Secretary Robert Gates visited Manama and held talks with the king in which he said he urged them to undertake rapid and significant reform.

Gates also said Washington was concerned that the longer the instability dragged on the more likely Iran, a Shiite theocracy, was to try to meddle in Bahrain's affairs.