Parties working to prevent Iran from participating in Syria peace talks in Switzerland next week will regret denying Tehran a role, Iran's foreign minister said on Monday.

"These parties will regret all the efforts they have undertaken to prevent the participation of Iran to find a solution and an end to the Syrian crisis," Mohammad Javad Zarif said at a news conference with his Lebanese counterpart in Beirut.

Tehran is the staunchest regional ally of the Syrian regime, which is scheduled to sit down with the opposition at peace talks in the Swiss town of Montreux on January 22.

But it has not been invited to the talks, though Damascus has said it should be and the Iranian government has said it would be willing to if it is invited without preconditions.

"When it comes to Iran's participation in Geneva II, Iran rejects all forms of preconditions on its participation," Zarif said.

"If the Islamic Republic of Iran receives a formal invitation, according to the criteria adopted for the invitations to the other parties, without preconditions, it will participate," he said.

The Syrian opposition accuses Iran of supplying the regime with weapons and funding to allow it to put down an uprising that began in March 2011 and has evolved into a brutal civil war.

Syria's government has said it will attend the Montreux talks, but insists President Bashar al-Assad's departure from power will not be on the table.

The opposition says Assad has no place in Syria's future and Britain's Foreign Secretary William Hague said Monday that Iran could attend the talks if it embraced political transition in Syria.

Iran has said Assad's future should be decided at the ballot box and Zarif warned Monday that outside parties should only play the role of mediators.

"The Syrian crisis must be resolved by the Syrian people and other parties should at the very least help to find a political solution and not act as judges imposing conditions for dialogue," said Zarif.

Iran was "prepared to participate actively and positively in finding a peaceful resolution to the Syrian crisis.

"We believe there is only one option in Syria, a peaceful resolution," he added.

Zarif is in Lebanon for a two-day visit that included meetings with Lebanese President Michel Sleiman and Hassan Nasrallah, the chief of the Iran-allied Shiite movement Hezbollah.

Zarif is due to visit Syria this week and will hold talks with Russian President Vladimir Putin on Thursday.

Iran must embrace Syria transition to attend talks: UK
London (AFP) Jan 13, 2014 - Iran could attend peace talks on Syria next week if it gives a "strong signal" that it will embrace a political transition to replace the current regime, British Foreign Secretary William Hague said Monday.

Hague said Iran was still providing support to Syrian President Bashar al-Assad's government, and that if it wanted to attend the talks in Switzerland it should instead agree to the principles set out at a first set of talks in Geneva in 2012, including a transitional government in Syria.

Iran has not been officially invited to the talks by UN Secretary General Ban Ki-moon.

"If you want to come, show very clearly that you're going to engage on the same basis as the rest of us," Hague said.

He added that a "signal of support" for a transitional government would be "a very helpful signal to Iran in getting them to Geneva II".

Addressing Britain's parliament, Hague said there was "no objection in principle to Iran in any quarter, certainly in Western nations, coming."

Russian Foreign Minister Sergei Lavrov and UN-Arab League envoy Lakhdar Brahimi both said earlier Monday that Tehran should be at the so-called Geneva II talks, but US Secretary of State John Kerry said Iran must first sign up to the Geneva I principles.

The talks are due to start on January 22 in Montreux, Switzerland.

Britain has in recent months resurrected its diplomatic ties with Iran, which were severed after protesters ransacked the British embassy in 2011.

On Syria, Hague said Britain would make a "major further donation" to a UN Syrian aid appeal at a pledging conference in Kuwait on Wednesday.

Hague confirmed that a British warship, HMS Montrose, would also help escort Danish and Norwegian vessels transporting Syrian chemical weapons away for destruction.

He also said Britain would supply specialist equipment for use on a US vessel on which Syrian chemical stocks are being neutralised.