Al-Qaida's Syrian affiliate and its allies seized the last regime-held military base in northwestern Idlib province on Wednesday, in the latest setback for President Bashar al-Assad's forces.

Al-Nusra Front and a coalition of mostly Islamist groups captured the Abu Duhur military airport after a siege that lasted two years, the Syrian Observatory for Human Rights monitor said.

Seven Indian nationals are missing in Yemen after air strikes hit their boats, as a Saudi-led coalition steps up attacks against rebels, the Indian foreign ministry said Wednesday.

One of the boats was travelling across the Red Sea from the Somalian port of Berbera to Mokha in Yemen when it came under fire on Tuesday, a foreign ministry spokesman said.    

At least three Russian military transport planes have landed in Syria in recent days, U.S. officials said Tuesday, as Washington worries about the sort of assistance Moscow is providing to Damascus.

The aircraft have landed at the airport in Latakia on Syria's Mediterranean coast over the past several days, U.S. officials told Agence France Presse on condition of anonymity.

Australian Prime Minister Tony Abbott on Wednesday bowed to pressure to increase refugee numbers in the face of the Middle East crisis and confirmed Canberra will also join U.S.-led air strikes on the Islamic State group in Syria.

With his hardline against asylum-seekers under intense scrutiny given the drama unfolding in Europe, Abbott said the government was acting "with our head as well as with our heart" to help the thousands of migrants fleeing the conflict.

NATO Secretary General Jens Stoltenberg on Tuesday voiced concern over reports of a Russian military build-up in Syria, warning that any support for Bashar Assad would escalate the bloody conflict.

"Yes, I am concerned by reports that Russia may have deployed military personnel and aircraft to Syria," Stoltenberg said in a public question and answer session on his Facebook page, in response to a question submitted by AFP.

Gunmen in Baghdad kidnapped an acting deputy justice minister of Iraq on Tuesday and wounded his driver, officials said.

A justice ministry official identified the man seized as Abdulkarim Fares, saying he is director general for financial and administrative affairs at the ministry as well as an acting deputy minister.

France carried out its first surveillance flights over Syria on Tuesday to prepare possible attacks on Islamic State jihadists, Foreign Minister Laurent Fabius said.

"These surveillance flights will determine what action can be taken when the time comes," Fabius told reporters.

NATO member Bulgaria said Tuesday it had refused permission to an unspecified number of Russian aircraft to cross its airspace late last week, amid growing U.S. fears that Moscow is boosting military support to Syrian President Bashar Assad.

"The planes were said to carry humanitarian aid but we had information -- that we had every reason to trust -- that the declared cargo was not the real one," foreign ministry spokeswoman Betina Zhoteva told AFP.

Media watchdog Reporters Without Borders (RSF) said Tuesday that a Sudanese journalist has been detained in Saudi Arabia without charge since July and his family fear he could be extradited to Khartoum.

Waleed al-Hussein founded the al-Rakoba website, which publishes news and opinion pieces critical of President Omar al-Bashir's government and has been blocked in Sudan several times since it started in 2005, RSF said in a statement.

The United States put three senior members of Hamas, a senior commander and two leaders freed by Israel in exchange for captive soldier Gilad Shalit, on its "terror" blacklist Tuesday. 

The State Department said Yehia Sinwar, Rawhi Mushtaha and the Palestinian group's military commander Mohammed Deif had been named "specially designated global terrorists" under U.S. law.