Syrian forces killed dozens of people in fierce fighting across the country Saturday, with some activist groups reporting more than 100 dead, just three days before a deadline set by a U.N. peace plan for troops to withdraw from urban areas.

Representatives of activist groups near the city of Hama described an attack on the nearby town of Latameneh, where demonstrations have been held since the beginning of the year-long uprising against President Bashar al-Assad’s rule.

More than 70 people died in the assault, including five members of the loosely organized group known as the Free Syrian Army, according to a member of the Syrian Revolution General Command who uses the nom de guerre Abo Adnan.

Other opposition groups reported dozens of people were killed elsewhere, including armed opponents of the government and members of the security forces. None of the accounts could be verified because Syria restricts journalists’ access.

The violence continued despite Syria’s agreement almost a week ago to implement a plan proposed by Kofi Annan, the joint U.N.-Arab League envoy to Syria, that requires troops to withdraw from towns by April 10 and calls for more access for humanitarian groups.

The U.S. ambassador to Syria, Robert Ford, who has left the country for security reasons, issued a statement Friday saying that the United States and the Friends of Syria group of nations sympathetic to the opposition are “closely monitoring whether these required actions [of the agreement] are occurring or not.”

Ford posted satellite images on the embassy’s Facebook page that he said showed places where armored vehicles and artillery units had been moved out of inhabited areas but remained close enough to fire on civilians. Two such places, he said, were Zabadani and Homs, both of which have a strong opposition presence.

“The regime and the Syrian people should know that we are watching,” Ford’s statement said. “The regime cannot hide the truth.”

Syrian state media reported that government officials have written to the United Nations asserting that terrorist groups and al-Qaeda “elements” have also stepped up operations since Annan’s plan was endorsed.

Last week, the International Committee of the Red Cross, whose operations have been limited, renegotiated its relationship with the Syrian government in a possible step toward fulfilling the requirement that aid organizations be able to work in Syria. A spokesman for the group said that a daily two-hour humanitarian cease-fire “was part of the discussion” but struck a cautious note, saying that the group would wait to see “what materializes.”

“We are more determined than ever to see an end to this crisis,” said Ahmad Fawzi, a spokesman for Annan, in a telephone interview. “I hope all the players will rise to this occasion and understand that it’s time to stop killing and start talking.”