* Kiev's ceasefire due to expire at 1900 GMT
* Poroshenko meets his security chiefs to discuss next step
* Talks with Russian, French, German leaders (Adds contact group to meet again)
By Richard Balmforth
KIEV, June 30 (Reuters) - Ukrainian President Petro Poroshenko called a meeting of his security chiefs on Monday to decide whether to extend a shaky ceasefire in the war against separatists that was due to lapse at 10 p.m. (1900 GMT).
Poroshenko consulted the national security and defence council after four-way telephone discussions with the leaders of Germany, France and Russia aimed at helping end the situation in Ukraine's Russian-speaking east where government forces have been battling pro-Russian separatists since April.
His office said the four leaders backed a further meeting of the so-called contact group involving separatist leaders, a former Ukrainian president, a senior representative of the OSCE rights and security body and Moscow's ambassador to Kiev.
The group, which seeks to defuse the crisis, would consider options for a new ceasefire between the opposing sides, work to set up effective border controls and secure the release of hostages on both sides.
But Poroshenko's office did not make clear whether he would recommend a further extension to the ceasefire from Monday night when he met his security chiefs. He is facing calls from some of them not to extend it because of Ukrainian military losses in the past seven days.
Since the ceasefire began on June 20, a total of 27 Ukrainian servicemen have been killed and 69 wounded, a statement tweeted by the foreign ministry said.
Before the meeting, Vitaly Yarema, the prosecutor-general, said: "We have to end this and clean our territory of terrorists and give people the chance of living in a normal country."
Poroshenko extended the original week-long ceasefire by 72 hours last Friday at the urging of the West and Russia, but many on the government side say the separatists are using the time to regroup and rearm.
The four-way telephone talks again brought Poroshenko together with German Chancellor Angela Merkel, French President Francois Hollande and Russian President Vladimir Putin.
Poroshenko had urged Putin on Sunday to strengthen Russian control over its borders to prevent militants and arms entering Ukraine after violence led to breaches of a truce there.
The European Union, which signed a landmark free-trade pact with Ukraine on Friday, has warned it could impose more sanctions unless pro-Russian rebels act to wind down the crisis in the east of the country by Monday.
Putin again urged that the ceasefire in eastern Ukraine be extended and a control mechanism to monitor the truce set up, with the participation of the Organisation for Security and Co-operation in Europe (OSCE), the Kremlin said in a separate statement after the talks on Monday.
"The leaders spoke in favour of convening a third round of consultations between Kiev and south-eastern regions as soon as possible," it added.
Hollande's office said Russia's and Ukraine's foreign ministers would be in touch later and that a contact group on Ukraine would meet to discuss implementing agreed moves.
Speaking after the presidents' call, Russian Foreign Minister Sergei Lavrov told Russian state TV that Moscow was ready to allow monitors from the OSCE security and rights watchdog and Ukraine's border guards to the Russian side of the border for joint control. (Reporting by Ingrid Melander in Paris; and Gabriela Baczynska in Moscow, Additional reporting by Elizabeth Pineau in Paris; Writing by Richard Balmforth; Editing by Tom Heneghan)