BAGHDAD, Iraq (CNN) -- A small Sunni Arab bloc ended its boycott of Iraq's parliament Saturday, boosting the appearance of national unity just days before key reports are due in Washington on Iraq's progress.
U.S. soldiers return to base after going after al Qaeda in Iraq militants outside Baghdad.
Saleh al-Mutlaq, who leads the National Dialogue Front, told CNN that the Sunni Arab group's 11 members of parliament returned to the 275-seat legislature after their demands were met.
"The government has agreed to allocate funds to displaced families ... and it has agreed to delay negotiations on the oil law until after Ramadan," he said in a telephone interview from Amman, Jordan.
Ramadan is the Muslim month of fasting, which begins next week.
"We are therefore today heeding the call of the speaker to end our boycott."
Al-Mutlaq said the decision also was based in part on some U.S. policy changes in Iraq.
"Americans were only talking with the Kurdish bloc and the Shiite bloc. Now, they are starting to be somehow fair," he said.
"They are working with tribes to get rid of al Qaeda and putting pressure on the militias."
Iraq's parliament is preparing to tackle key legislation in response to U.S. benchmarks aimed at measuring Iraq's progress toward national unity.
Gen. David Petraeus and U.S. Ambassador to Iraq Ryan Crocker are to appear before Congress this week to present their assessments.
"We are hoping that the Americans are realizing that the sectarian parties or Islamic parties cannot govern Iraq, and they should support the national liberal trend in Iraq," al-Mutlaq said.
In spite of the political progress, at least 15 civilians were killed in separate explosions around Iraq, officials said Saturday.
At least 10 people were killed and 30 wounded when a suicide car bomb exploded Saturday evening outside a police station in the Baghdad neighborhood of Sadr City, an Interior Ministry official said.
The bomb went off at 6:30 p.m. (10:30 a.m. ET) in the densely populated and predominantly Shiite district.
A hand grenade exploded in a market south of the capital in Kufa, killing at least three Iraqi civilians and wounding six others Saturday afternoon, Najaf police said.
Following the blast, police said Kufa and Najaf -- both major Shiite cities -- were shut down for two hours.
Earlier, at least two civilians were killed and four were wounded when a mortar slammed into a residential area in eastern Baghdad, an Iraqi Interior Ministry official said.
The blast went off before noon in the capital's Baladiyat district.
Separately, U.S.-led coalition forces arrested five suspected terrorists in morning raids targeting al Qaeda in Iraq leaders and bomb networks in northern Iraq, the U.S. military said.
The raids, conducted in Kirkuk and Mosul, were part of an ongoing effort to "put pressure on al Qaeda's networks to squeeze them out of their hiding places," spokesman for Multi-National Force-Iraq, Lt. Col. Charles Perenick said.
Also, eight unidentified bodies were found in Baghdad by Iraq police Friday, bringing this month's toll to 87.
Slain bodies are found daily around the capital and police suspect these deaths have evolved out of Sunni-Shiite sectarian vendettas.
About 26,000 U.S. and Iraqi forces are taking part in the offensive in northern Iraq, the U.S. military said.
The operation, Lightning Hammer II, is an extension of an earlier operation in Diyala province.
About 14,000 Iraqi security forces stationed throughout Nineveh province and 12,000 U.S. soldiers are conducting the operation, which started Wednesday evening.
The military said the operation "follows Lightning Hammer I ... to deny al Qaeda safe haven in the provinces" of Salaheddin, Nineveh, Diyala, and Kirkuk.
The military said the original Operation Lightning Hammer -- August 13 to September 1 -- ousted militants from the Diyala River valley, northeast of Baquba, the capital of Diyala province. E-mail to a friend
CNN's Raja Razek and Mohammed Tawfeeq contributed to this report.
All About Iraq War • Al Qaeda in Iraq
Un bloque sunita – el último que faltaba – se presentó al parlamento así terminando el boicot de varios grupos que se habían retirado del gobierno de Iraq hace tres meses.

El líder del Frente de Diálogo Nacional declaró que sus condiciones habían sido cumplidas, por lo que su partido volvería al parlamento.

"El gobierno acordó destinar fondos a familias desplazadas ... y ha acordado retrasar negociaciones en la ley del petróleo hasta luego del Ramadan", declaró el líder, Saleh al-Mutlaq, a la CNN.

El Ramadan es una costumbre musulmana que consiste en ayunar por un mes y que comenzará la semana entrante.

Además, el líder al-Mutlaq también agregó que su decisión también se basaba en un cambio de la política estadounidense.

"Los americanos sólo hablaban con el bloque kurdo y el bloque chiita. Ahora, están empezando a ser algo justos", declaró. "Están trabajando con tribus para deshacerse de Al Qaeda y poner presión en las milicias".

Con este fin del boicot, al-Mutlaq aseguró que sus 11 miembros del parlamento volverían a la legislatura de 275 miembros. El principal bloque sunita de Iraq, el Frente de Acuerdo, junto con facciones leales a Moqtada Sadr, ya habían dado por terminados sus boicots recientemente.

Sin embargo, al-Mutlaq advirtió: "Necesitamos un gobierno liberal, necesitamos un gobierno laico. Sin un gobierno así la violencia continuará.

"La violencia crecerá nuevamente ya que las personas perderán la esperanza si nada cambia en el aspecto político".

A pesar de este progreso político, al menos 15 civiles murieron hoy en distintos ataques.

Un ataque involucrando un auto-bomba causó la muerte de nueve personas en el distrito chií de Sadr City en Bagdad. Hubo al menos otros 30 heridos luego de la detonación producida a las 6:30 p.m. (10:30 a.m. ET), según declaró el Ministro del Interior.

En otros incidentes:

* Cuatro personas murieron luego de que explotara una granada en un supermercado en la ciudad chií sagrada de Kufa, declararon oficiales médicos.
* Como resultado de una bomba dirigida a una casa en el distrito oriental de Baladiyat en Bagdad, dos personas resultaron muertas.
* Tiradores en Najaf además mataron a Mohammed al-Qarawi, el director de asuntos tribales perteneciente al grupo chií de Moqtada Sadr.