Britain cannot afford just to "sit on the sidelines" and watch the slaughter continue in Syria, Foreign Secretary William Hague says.
He refused to rule out the prospect that Britain could arm the Syrian rebels, despite a warning from President Bashar Assad that supplying weaponry to the opposition could ignite a conflict across the entire Middle East.
Mr Hague - who is set to announce further non-lethal assistance to the rebels later this week - dismissed the Syrian leader as "delusional".
He said that the UK would continue to step up support for the opposition as long as there was no diplomatic or political breakthrough in the two year long conflict.
"The longer this goes on the greater the danger that extremism takes hold, the greater the danger of destabilising neighbouring countries, and the greater the extreme humanitarian distress involved. So we cannot just sit on the sidelines and watch this," he told BBC1's The Andrew Marr Show.
"We will be doing more and we will have to steadily do more if there is no diplomatic or political breakthrough. The situation in Syria now is too dangerous to the peace and security of that entire region and thereby to the world to ignore it.
"I don't rule anything out for the future. If this is going to go on for months or years and more tens of thousands of people are going to die and countries like Iraq and Lebanon and Jordan are going to be destabilised it is not something we can ignore.
"These are the reasons why we can't just sit it out in Syria."