* More than 100 arrested, including union officials
* Union accuses government of oppression
* Leftist suicide bomber killed guard in attack (Adds quotes, details, background)
By Daren Butler
ISTANBUL, Feb 19 (Reuters) - Police arrested more than 100 people including union officials in raids across Turkey on Tuesday targeting a militant leftist group behind a suicide bomb attack on the U.S. embassy.
Turkey is an important U.S. ally in the Middle East with common interests ranging from energy security to counter-terrorism. Leftist groups strongly oppose what they see as imperialist U.S. influence over their country.
Tuesday's raids unfolded after a member of the Revolutionary People's Liberation Party-Front (DHKP-C) blew himself up at an entrance of the U.S. embassy in Ankara on Feb. 1, killing a Turkish security guard.
The DHKP-C, virulently anti-American and listed as a terrorist organisation by the United States and Turkey, has staged a series of deadly attacks on police stations over the last six months.
Police issued arrest warrants for 167 people in 28 provinces across Turkey and by midday detained more than 100 people, among them Akman Simsek, a senior official from public workers union confederation KESK, state-run Anatolian news agency reported.
KESK, a leftist trade union group, demanded the release of their detained members, blaming the raids on an "empire of fear" created by the Islamist-rooted AK Party of Prime Minister Tayyip Erdogan.
"According to information obtained by our confederation, more than 100 people have been detained," KESK said. It did not say how many of those detained were members of the union.
"We will stand up against the fascist policies of the AKP government and will not bow down in front of the masters oppression and tyranny," it said. "Long live our struggle!"
It said 59 of its leaders and members had previously been detained over the last year due to their union activities.
Anti-terror police arrested 15 people in the western coastal province of Izmir and two other provinces in operations targeting a group called the Revolutionary Civil Servant Movement, believed to be linked to the DHKP-C, Anatolian said.
Police searched Simsek's offices in the capital Ankara and Antalya and seized a computer hard disc and documents.
Around half of the total were detained in Istanbul with the others scattered around provinces from the whole of Turkey, including the northwestern province of Tekirdag, where police detained a local official of a teachers' union, Anatolian said.
Turkish police have carried out a series of major operations in recent years targeting secularists, military officers, Kurds and leftists on charges of terrorist activities. Opposition groups accuse Erdogan of using those investigations for a broader, authoritarian crackdown on dissent.
This month's attack on the U.S. embassy followed the detention of dozens of people in raids targeting people linked to the DHKP-C in January.
In a statement claiming responsibility for the attack, the DHKP-C accused Washington of using Turkey as its "slave", describing Erdogan as a U.S. "puppet" and warning that he too was now a target.
A photograph accompanying that statement had shown the bomber, Ecevit Sanli, wearing a black beret and military-style clothes and with an explosives belt around his waist.
The DHKP-C also called on Washington to remove Patriot missiles deployed on Turkish soil to protect NATO member Turkey against a spillover of the war in neighbouring Syria. (Writing by Daren Butler; Editing by Nick Tattersall and Mark Heinrich)