RIYADH, Sept 4 (Reuters) - A well-known Saudi reform activist and his brother have been ordered to appear in court on charges including inciting protests by women, a colleague said on Tuesday.

Abdullah al-Hamed and his brother Isa are expected to appear in a criminal court in the town of Buraida north of Riyadh over an incident in July where the wives of Saudi men in indefinite detention staged a public protest.

"They were ordered three days ago to appear in court on charges of provoking women to stage a sit-in and trying to break a security cordon," said Khaled al-Omair, legal representative for the two men.

Omair said the penalty if found guilty was not clear but it could be at least one year in prison.

Hamed was detained for several days in July along with women who gathered outside state security offices in Buraida to demand that their husbands face trial or be released, and to raise complaints about mistreatment in prison.

The Interior Ministry said at the time that Hamed and his brother had violated a security cordon around the house of one of the protesters. A spokesman was unavailable for comment on Tuesday.

The government says about 3,000 people are in detention out of a total of 9,000 arrested since Islamist militants allied to al Qaeda launched a violent campaign in May 2003 to topple the U.S.-allied monarchy and expel foreigners.

Activists say many of them have little or no connection to militant groups.

Hamed was sentenced in 2005 to seven years in jail on charges of sowing dissent and challenging the royal family in the kingdom, which has no elected parliament or political parties.

Later that year King Abdullah pardoned Hamed and two other reformers convicted in the same case.

Hamed was a key mover behind a petition to King Abdullah this year asking for more action on political reforms.

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