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* Executions, clashes with Kurdish group on the rise

* Iran's Kurdish minority complain of oppression, discrimination

* Gains made by Kurds in Syria, Iraq add to tensions

* Family says activist was tortured

By Bozorgmehr Sharafedin

DUBAI, Aug 27 (Reuters) - Iran executed a Kurdish activist on Wednesday accused of killing a public prosecutor, the second such case this month, rights groups said, as Iran, unsettled by Kurdish gains in the region, tightens the screws on its Kurdish minority.

Behrouz Alkhani, 30, was convicted in 2011 of having ties to the Party of Free Life of Kurdistan (PJAK), an outlawed group that seeks self-governance for Iran's Kurds and has links to Turkey's militant Kurdish Workers' Party (PKK).

He was also found guilty of being involved in the shooting of a public prosecutor in West Azerbaijan Province in 2010, which the authorities blamed on the PJAK.

His brother, Peyman Alkhani, confirmed to Reuters that he was a member of PJAK, but said he never took up arms.

Amnesty International called Alkhani's trial "grossly unfair" and said his execution was a "denigration" of both Iranian and international law because his sentence was under appeal at the Supreme Court.

Iranian officials have made no comments about the case.

Earlier this month, Iran executed another PJAK-member, Sirvan Nezhavi. Within days, PJAK's military wing retaliated by attacking a Revolutionary Guards' base in Kamyaran some 20 km (12 miles) from the border with Iraq.

The Kurdish fighters said they killed 12 Iranian soldiers, but Iran only confirmed five deaths.

KURDS ON THE RISE

Many Kurds in Iran complain of oppression of their cultural identity and of discrimination, mainly for government jobs, and want a regional government like that of the Kurds in Iraq.

A ceasefire between the government and PJAK was signed in 2011, when Iran said it would suspend executions of Kurdish political prisoners if PJAK stopped its attacks.

Both sides regularly violated the deal, but in recent months the number of clashes has shot up.

Iran's seven million Kurds make up around 10 percent of the population. Most live in Kurdistan, a region in the northwest on the border with Iraq. It is among the most politically active regions in Iran, where little dissent is tolerated. In recent months, workers and activists have held a series of demonstrations and strike actions calling for equal rights.

Iranian President Hassan Rouhani visited Kurdistan last month, his first visit after Iran reached a historic nuclear deal with world powers in July, a powerful symbol that the country was choosing the path of its moderate politicians over its hardliners.

However, on the Kurdish question, the hardliners in the judiciary and Revolutionary Guards currently prevail.

"Iran wants to make it clear that nuclear deal should not create any new expectation among the Kurds to seek more freedom," Hemn Seyedi, a political analyst based in London, said.

Iran has also grown wary as Kurds around the region have made significant political and territorial gains, as well as some powerful new friends.

In Iraq and Syria, Kurdish fighters have become key allies to a U.S.-led coalition fighting Islamic State, taking on the ground offensive while the fighter jets back them up from the air.

Washington considers the PKK a terrorist group, but cooperates with related entities such as the Democratic Union Party (PYD) in the Syria and Kurdish peshmerga forces in Iraq.

However, Turkey last month began a campaign of air strikes against the PKK after the militants stepped up attacks, saying Turkey had violated a ceasefire agreement.

"Iran is also worried about the movement of PKK fighters near its Iraqi border. PKK fighters might come to Iran to escape recent Turkish bombardment. That's why Iran is showing a stronger fist to Kurds in recent months," said analyst Seyedi.

Peyman Alkhani said that alongside his brother, five other Kurds were executed on charges of drug dealing. But unlike the others, Behrouz's body was not returned to his family.

"We were told we are not allowed to hold any commemoration ceremony," he added.

Alkhani said his brother was held in solitary confinement for over a year and that he was tortured. Once, the family went to visit him and saw that all his fingers were broken.

Reuters was unable to independently verify the family's account of torture inside the prison.

(Editing by Raissa Kasolowsky) ((Bozorgmehr.Sharafedin@thomsonreuters.com Twitter: @bozorgmehr;))

Keywords: IRAN RIGHTS/KURDS