BEIRUT (AP) — The U.N. humanitarian chief headed to the shattered central Syrian city of Homs today, where activists have accused regime forces of trying to cover up evidence of a monthlong military assault and alleged execution style killings.

Valerie Amos arrived in Damascus earlier in the day and met the foreign minister before departing for Homs, said a U. N. spokesman in Syria, Khalid al-Masry. The government had rebuffed an earlier request by Amos to visit the country this month as regime troops attacked the Baba Amr neighborhood in Homs, finally wresting it back from rebels last Thursday.

Despite international appeals, the Syrian government still has not allowed any aid workers into Baba Amr, saying there was a security risk. But activists say the government has been engaged in a “mopping-up” operation to hide their activities.

Al-Masry said he did not know if Amos would visit Baba Amr.

Amos has said the aim of her visit is “to urge all sides to allow unhindered access for humanitarian relief workers so they can evacuate the wounded and deliver essential supplies.”

The trip comes as Syrian President Bashar Assad defies mounting international pressure to end the year-old crackdown on an uprising against him.

According to state news agency SANA, Assad said Tuesday that he will continue to confront “foreign-backed terrorism.” Since the uprising began last March, he has blamed armed gangs and foreign terrorists for the unrest, not protesters seeking change.