President Barack Obama said Wednesday he had not yet signed off on a plan to strike Syria, but action appeared likely after Washington abandoned the hunt for a last-minute U.N. mandate.

Political uproar in London, meanwhile, cast doubt on whether Britain will join American military action to punish President Bashar Assad's regime for a chemical weapons attack, should the response take place before next week.

Qatar's new emir, Sheikh Tamim bin Hamad Al-Thani, on Wednesday approved border and anti-crime accords with Saudi Arabia, in another sign of improving ties between the two Gulf neighbors.

State news agency QNA said the emir endorsed an accord on cooperation between border authorities in Qatar and Saudi Arabia, and another on the fight against crime.

A resolution condemning Syria's alleged poison gas use has stalled in the U.N. Security Council due to Russian "intransigence," the United States said Wednesday.

"We see no avenue forward, given continued Russian opposition to any meaningful Council action on Syria," State Department deputy spokeswoman Marie Harf told reporters as Washington and Western allies mull a possible strike on Syria after last week's alleged chemical weapons attack by Syrian regime forces.

British Foreign Secretary William Hague said Wednesday that talks at the U.N. over a response to the Syrian crisis would continue "over the coming days", as the British parliament prepares to debate possible military action.

Britain sought backing from the U.N. Security Council on Wednesday, submitting a draft resolution to the five permanent members calling for action to protect Syrian civilians.

Bahrain's national dialogue launched in February and aimed at ending the Gulf monarchy's political deadlock since a 2011 Shiite-led revolt resumed on Wednesday after a two-month summer break.

Opposition and government representatives took part in the Manama talks, participants said.

The Turkish army has stepped up its "vigilance" following last week's suspected chemical weapons attack in Syria, Foreign Minister Ahmet Davutoglu said Wednesday.

"Since the chemical weapons (attack), we are of course in a situation of heightened vigilance," he told reporters while paying homage to Turkish soldiers patrolling the country's common border with Syria.

Anticipating a Western-led military strike on Syria's regime, Human Rights Watch warned Wednesday that any such intervention must include every possible effort to protect the civil war torn nation's civilians.

The U.S.-based rights group stressed it was not taking up a position on possible military action, which Washington and other Western powers have hinted was due after alleged poison gas attacks last week near Damascus.

British Prime Minister David Cameron will Thursday make the case to parliament for targeted military action to halt the use of chemical weapons in Syria but faces opposition from lawmakers haunted by the Iraq war.

Cameron and his ministers met with defense chiefs Wednesday and agreed that President Bashar Assad's regime was behind the chemical attack near Damascus last week, Downing Street said.

Two Syrian Arab Red Crescent workers and an unknown number of civilians were killed by a mortar shell in the flashpoint central Syrian city of Homs, the IFRC said Wednesday.

Wassim Muselli and Yusef Al Kens, who both worked for the Homs branch of the Red Crescent, were killed on Tuesday in front of their offices, the International Federation of Red Cross and Red Crescent Societies (IFRC) said in a statement.

The Organization of Islamic Cooperation on Wednesday condemned alleged poison gas attacks in Syria, blaming the government and calling for "decisive action" in response.

The world's largest grouping of Muslim nations "stressed the need to hold the Syrian government legally and morally accountable for this heinous crime and to bring its perpetrators to justice".