British Foreign Secretary William Hague said on Saturday he has seen "some evidence" that Bashar Assad's regime is preparing to use chemical weapons against Syrian rebels, AFP reported.
"We have seen some evidence of that," Hague said to reporters in Manama at a regional security conference.
"We and the US, as I said in parliament this week, have seen some evidence of that and that is why we have issued strong warnings about it. We have done so directly to the Syrian regime," AFP quoted him as saying.
Asked what evidence had been presented, Hague commented: "We absolutely cannot be specific about that because clearly those are intelligence sources that these things come from."
Commenting on Western intervention, Hague stated that military intervention had not been ruled out, adding: "We have contingency plans concerning chemical weapons but will not disclose them," according to AFP.
However, UN Secretary-General Ban Ki-moon said on Friday he was not aware of any confirmed reports that Syrian President Bashar Assad was preparing to use chemical weapons but that if he did so it would be an "outrageous crime."
Several Western countries have issued warnings this week to Assad's government not to use chemical arms, many citing intelligence that Washington has said showed it might be preparing to use poison gas. Hague said Britain had joined with the United States in delivering a strong message to President Bashar Assad's government.
"Recently we have been receiving alarming news that the Syrian government may be preparing to use chemical weapons. We have no confirmed reports on this matter," UN chief Ban said after visiting a Syrian refugee camp in Turkey.
"However, if it is the case, then it will be an outrageous crime in the name of humanity," he said. "I know that many world leaders have added their voices urging him not to use it and warning him that it will create huge consequences."
Ban said he had spoken on Thursday with the head of the Organization for the Prohibition of Chemical Weapons about ways to investigate the reports but no concrete plan had yet emerged.
He called on world powers and the UN Security Council to unite and take action to end the Syrian conflict, saying only a political solution could stop the bloodshed. But he said the international community had not yet started to discuss the possibility of arranging safe passage for Assad and his family out of Syria should he be persuaded to leave.
Earlier this week, Prime Minster Binyamin Netanyahu addressed raised concerns that Syrian President Bashar Assad could be preparing to use chemical weapons in his fight to survive against opposition forces, stating that Israel was monitoring the situation closely. "These weapons cannot be used or transferred to terrorist organizations," Netanyahu said.
Israel has also asked Jordan on a number of occasions for “permission” to bomb Syrian chemical weapons sites, according to a report published earlier this week by The Atlantic, citing intelligence sources in both countries.