RIYADH (AFP) - A Saudi woman has been sentenced to six years in prison for "acts of sedition" including pledging allegiance to the Islamic State in Iraq and Syria (ISIS), newspapers reported on Thursday (May 12).

A court in Riyadh issued the sentence against the unnamed 27-year-old on Wednesday, the Saudi Gazette said.

But Al-Hayat daily reported that the judge decided to keep her in jail for only three years after she expressed "regret" for her "acts of sedition" and suspended the rest of the sentence.

She will however also be banned from travelling abroad for six years, it added.

The woman was convicted of pledging allegiance to Abu Bakr al-Baghdadi, leader of ISIS, which has seized territory in Iraq and Syria.

ISIS has claimed attacks in Saudi Arabia against members of the minority Shi'ite community and the Saudi security forces.

She posted messages on Twitter supporting a deadly attack on security forces, and hung posters at a mosque and on utility poles to seek the release of a suspected militant, Saudi Gazette said.

She also reportedly called for disobedience against the kingdom's rulers.

Saudi Arabia is part of the US-led coalition bombing ISIS in Iraq and Syria.

Saudi political and religious leaders routinely denounce ISIS attacks - at home and abroad - as contrary to Islam.

Still, a report last year by the inter-governmental Financial Action Task Force said Saudis comprised the second largest nationality among "foreign terrorist fighters" with ISIS.

Baghdadi, the ISIS leader, has called Saudi Arabia's Sunni rulers "apostate tyrants" and urged Saudis to rise up against them.

The verdict against the woman coincided with an upsurge of security incidents in Saudi Arabia over the past week.

Saudi police on Monday shot dead a suspected militant in the western province of Taif a day after one of their colleagues was killed in a shootout, the Interior Ministry said.

On May 5, another police officer was shot dead and four suspected militants were killed during a raid in an area between Taif and the region of Mecca, home to Islam's holiest sites.