By Daren Butler

ISTANBUL (Reuters) - Turkish authorities are seeking two suspected Islamic State militants thought to be linked to last week's Istanbul airport attack and believed to be in hiding near the border with Syria, a Turkish newspaper said on Wednesday.

Turkey has jailed a total 30 suspects pending trial over the triple suicide bombing at Ataturk Airport, which killed 45 people and wounded hundreds, the deadliest in a series of bombings this year in Turkey.

Turkish officials are not commenting on reports about the investigation, although one government official has said the attackers were Russian, Uzbek and Kyrgyz nationals. President Tayyip Erdogan has said Islamic State militants from the former Soviet Union were behind the attack.

On Tuesday he described the Sunni hardline group as a "dagger plunged into the chest of Muslims".

The pro-government Yeni Safak newspaper said two Islamic State suspects were believed to be hiding in woodland in the Yayladagi area of Turkey's southern Hatay province and could be planning to change their appearance and joint rebel groups in Syria.

It said they were from Dagestan, a mainly Muslim province of Russia's North Caucasus region. The paper did not identify its sources for the story.

"Security and intelligence units have taken top level measures in the area to capture the terrorists given the possibility that they could cross into Syria," it said.

Other members of the same Islamic State team had fled to the Kilis and Gaziantep areas further east and were hiding there, while militants from the Caucasus were using fake identity papers and were receiving support from IS cells, it said.

EID AL-FITR ATTACKS

The Istanbul bombing was followed by major attacks in Bangladesh, Iraq and Saudi Arabia in the past week, all apparently timed for the run-up to Eid al-Fitr, the holiday marking the end of the Ramadan holy fasting month.

"Using sacred Islam's name, exploiting it, this terrorist group which spills Muslim blood has gone as far as attacking the town where the mosque and blessed remains of our Prophet are located," Erdogan said in a speech on Tuesday.

"Daesh is a dagger plunged into the chest of Muslims. Whoever gives support to this group, whether out of sectarian fanaticism or another motive, commits the same sin," he said, using an Arabic acronym for Islamic State.

Interior Minister Efkan Ala said on Tuesday that 15 of 30 people remanded in custody were foreigners from various countries. Yeni Safak said all 11 of the foreign suspects jailed on Tuesday were Russian nationals, while four of the 13 suspects remanded in custody on Sunday were foreigners.

In last week's attack, three bombers opened fire to create panic outside the airport before two of them got inside and blew themselves up. The third militant detonated his explosives outside at the entrance to the international arrivals terminal.

The Kremlin said on Wednesday it believed the Istanbul airport attack could be a result of Turkish and European security services ignoring Moscow's signals about suspected terrorists hiding in Turkey and Europe.

"Over the past many years, the Russian side ... has informed our Turkish and European colleagues that persons suspected of being linked to terrorism ... find shelter both in Turkey and in a number of other European countries," Kremlin spokesman Dmitry Peskov told reporters.

"In most cases such signals from the Russian side have not been given proper attention or any reaction by our colleagues. To our regret, these (Istanbul attacks) can be a consequence of such disregard."

Moscow says that thousands of Russian citizens and citizens of other former Soviet states have joined Islamic State, traveling through Turkey to reach Syria. Russia fought two wars against Chechen separatists in the North Causcasus in the 1990s, and more recently has fought Islamist insurgents in Dagestan.

Russia and Turkey have been at odds over Moscow's support for Syrian President Bashar al-Assad and Turkey's backing of rebels opposed to him, especially since last year when Turkey shot down a Russian warplane near the border.

But recent weeks have seen a thaw in relations between the two countries, with both citing a need to bury their differences to fight the common Islamic State foe.

(Editing by David Dolan and Ralph Boulton)