US officials held meetings with Syria's security chief Ali Mamlouk

US intelligence and defence officials met with Syria's security chief Ali Mamlouk in Damascus, according to multiple sources, seven years after severing diplomatic links with President Bashar al-Assad's government and backing the Syrian opposition.

Two senior US intelligence officials, speaking on the condition of anonymity, told Reuters that an American delegation met with Syrian officials. 

The officials said the meeting was part of an "ongoing dialogue with members of the Assad regime" about driving the Islamic State group (IS) from Syria, Damascus' stockpile and use of chemical weapons, including chlorine, and the fate of American journalist Austin Tice, who US officials believe the Syrian government or its allies are holding. 

A US State Department spokeswoman said on Wednesday that a report that US officials visited Damascus in June to meet with Syrian officials did not reflect reality.

Another official in the regional alliance backing Assad also confirmed to Reuters that the meetings took place.

An earlier report released by Lebanese newspaper al-Akhbar, which is sympathetic to the Syrian government, which said that a meeting took place between US officials and Mamlouk for four hours near Damascus International Airport. 

Al-Akhbar reported that the US officials demanded the withdrawal of Iranian forces from southern Syria and data on "terrorist groups", including foreign fighters, and had also requested a role in the oil business in eastern Syria.

Mamlouk said Damascus would not cooperate with Washington on security issues until they had normalised ties and he also demanded a complete withdrawal of US forces from Syria, al-Akhbar reported.

The regional alliance source told Reuters that most details in the al-Akhbar report were correct.

Since Assad violently cracked down on protests against his rule in 2011, Washington has backed the Syrian opposition and some rebel groups during the civil war.

However, last year US President Donald Trump ordered the shutting down of a CIA-run military aid programme.

These reports come after the United States said it will join United Nations-led talks in Geneva next month to discuss a new Syrian constitution, a State Department official said on Tuesday.

"The United States has accepted the invitation from UN Special Envoy for Syria Staffan de Mistura to participate in talks in Geneva on 14 September," a State Department official said.

Mamlouk, who heads the National Security Bureau, is regarded as one of Assad's closest security advisors. He holds the military rank of major general and is on the European Union's sanction list. 

Earlier this year, Mamlouk was reported to have met with Italian officials in a bid to normalise relations between Syria and the West. 

Bruno Kahl, president of Germany's Federal Intelligence Service, has emphasised the need for contacts with Syria to gain information on IS and al-Qaeda.