* Hague says strong case for lifting or amending embargo
* Germany "reluctant" to lift ban
* France, UK worried about Assad's willingness to use chemical weapons (Previous Brussels)
By Adrian Croft and Conor Humphries
DUBLIN, March 22 (Reuters) - France and Britain stepped up their drive on Friday for the European Union to lift its arms embargo to help Syrian rebels, but ran into strong opposition from other member countries who said sending more weapons could worsen the crisis.
British Foreign Secretary William Hague said as he arrived for an EU foreign ministers' meeting in Dublin that there was a "very strong case" for lifting or seriously amending the ban on sending weapons to the opposition when EU sanctions on Syria come up for renewal on June 1.
Rebels fighting forces loyal to Syrian President Bashar al-Assad have called on Western powers to do more to help them win a two-year-old civil war that has killed 70,000 people.
But Germany, Austria, Sweden and other states fear a proliferation of guns could fuel regional conflict and arm Islamist militants.
"We have to help and to support the (Syrian) people ... but ... we have to avoid a conflagration," German Foreign Minister Guido Westerwelle told reporters in Dublin.
Before the meeting, Hague and his French counterpart Laurent Fabius wrote to EU foreign policy chief Catherine Ashton setting out their arguments, saying they were "increasingly concerned about the regime's willingness to use chemical weapons".
The Syrian government and rebels have accused each other of using a chemical weapon in clashes near the northern city of Aleppo on Tuesday that killed 26 people. However, a U.S. official has said it increasingly appeared a chemical weapon was not used.
All 27 EU states would have to agree to renew or change the arms embargo and other sanctions. If they cannot agree, all EU measures against Syria, including asset freezes and travel bans, would collapse on June 1.
Opponents of Britain and France's drive to lift the ban calculate London and Paris will not push the issue to the point where it could lead all the sanctions to fall.
French officials have suggested Paris was using the threat of lifting sanctions primarily as a way of piling more pressure on Assad.
However, Hague and Fabius wrote in the letter: "It is increasingly difficult to argue the case for retaining the overall sanctions regime if those sanctions do not exempt the support that the opposition now need."
Hague and Fabius also signalled their readiness to compromise by saying they would accept "some very serious amendment" of the arms embargo, short of its complete lifting.
The embargo was previously amended in February to allow non-lethal assistance for the opposition.
Austrian Foreign Minister Michael Spindelegger said he could not see any reason for a compromise. "We are totally against so I can't see where there could be a compromise," he said.
If the arms embargo were lifted, Spindelegger said it would make it very difficult for Austria to leave several hundred troops on the Israeli-occupied Golan Heights as part of a U.N. peacekeeping force, because the EU would be perceived as taking sides in the Syria conflict.
No decision is expected at the foreign ministers' meeting which ends on Saturday. The issue is likely to be discussed further in EU working groups. (Additional reporting by Justyna Pawlak in Brussels; Editing by Andrew Heavens)