BEIRUT (AP) — Gunmen shot dead a journalist for a pro-government newspaper near Damascus on Tuesday, Syria’s official news agency said, as fighting between rebels and regime troops raged in and around the capital with opposition fighters pushing their way closer to the seat of President Bashar Assad’s power base.

The rebels have notched a series of tactical victories in recent weeks, overrunning two air bases near Damascus and capturing a hydroelectric dam in the north. With the Syrian regime feeling squeezed, U.S. officials said intelligence reports show Assad may be readying his chemical and biological weapons and may be desperate enough to use them.

The heavy fighting around the capital — the heaviest since July — prompted the United Nations on Monday to announce it was withdrawing most of its international staff from Syria due to deteriorating security in the country.

The Britain-based Syrian Observatory for Human Rights said Tuesday’s clashes between rebels and troops loyal to Assad are taking place in Beit Saham, Akraba and Yalda suburbs, as well as near the capital’s international airport. The Observatory relies on reports from activists on the ground.

The Damascus suburbs, which have been opposition strongholds since the uprising against Assad began in March 2011, have been the scene of heavy fighting since last week following the start of an army offensive to regain lost territory around the capital.  Assad’s forces have so far repelled major rebel advances on the capital, though their hold may be slipping.

Syria’s official SANA news agency said a journalist for the state-run Tishrin newspaper was killed near his home in al-Tadhamon suburb of Damascus. Naji Assaad was “assassinated by an armed terrorist group” Tuesday morning on his way to work, SANA said. The regime refers to rebels fighting to topple Assad as terrorists.

The Syrian uprising began with peaceful protests in March 2011, but has since morphed into a civil war that activists say has killed more than 40,000 people.

Washington has so far declined to intervene in the crisis, saying doing so could worsen the conflict.

On Monday, U.S. officials said the White House and its allies are weighing military options to secure Syria’s chemical and biological weapons, after U.S. intelligence reports show the Syrian regime may be readying those weapons and may be desperate enough to use them. 

President Barack Obama pointedly warned Assad not to use the weapons, saying that such an act would be a “tragic mistake” to which Assad and members of his regime would be held accountable.

Syria is believed to have several hundred ballistic surface-to-surface missiles capable of carrying chemical warheads, and a U.S. defense official said American and allied intelligence officials have detected activity around more than one of Syria’s chemical weapons sites in the last week. 

Syria’s Foreign Ministry said Monday that Syria “will not use chemical weapons — if there are any — against its own people under any circumstances.”

The comments from the ministry came just hours after Lebanese security officials said Jihad Makdissi, the Foreign Ministry’s polished spokesman, flew from Beirut to London.

It was not clear Tuesday whether Makdissi had defected.  He is known for defending the regime’s crackdown on dissent in fluent English.