* PKK rebels suspected
* Iraq repairs continue
* No timeframe for restored flow
(Adds detail, background)
KIRKUK, Iraq/DIYARBAKIR, Turkey, July 4 (Reuters) - A bomb planted by suspected PKK separatist rebels in Turkey and a technical fault in Iraq have halted pumping on the Kirkuk to Ceyhan pipeline, officials said on Sunday.
The bombing by the Kurdistan Workers Party (PKK) added a new dimension to the threats against the pipeline, which carries around a quarter of Iraq's oil exports, after the rebel group called off a 14-month ceasefire in June.
The explosion late on Saturday took place near the town of Midyat in Mardin province, near the border with Syria, Turkish security sources said. Crew workers from Turkey's state-run pipeline operator BOTAS were working on Sunday to repair the pipeline so that pumping can resume.
On the Iraqi side of the border, a technical problem on the pipeline that halted pumping late on Thursday was taking longer to fix than expected, sources at Iraq's North Oil Co said.
Iraqi oil officials said a technical team was continuing the maintenance and repair works, but gave no further details about when they expected to restore the flow of oil.
The 960 km (600 mile) pipeline carries an average 500,000 barrels of oil per day from Iraq's northern oilfields around Kirkuk to Turkey's Mediterranean port of Ceyhan, where it is loaded onto tankers for export.
Sabotage and technical problems kept the Iraq-Turkey route mostly idle until 2007 following the 2003 U.S.-led invasion of Iraq.
Security has improved but insurgents still target the pipeline from time to time, and it also suffers frequent technical issues because of its age and poor maintenance over the years.
Attacks on the Turkish side of the border had to date been far less common.
In recent weeks, the PKK has stepped up attacks on the Turkish military after ending the ceasefire. (Reporting by Mustafa Mahmoud; Additional reporting by Ibon Villelabeitia in Istanbul; Writing by Ahmed Rasheed; Editing by Will Waterman)