Internet and telephone lines were largely restored across Syria on Saturday after a two-day blackout, according to activists, as fighting raged around Damascus International Airport between rebels and government forces.

“Mobile coverage and Internet are back to work in most of the Syrian cities,” the Britain-based Syrian Observatory for Human Rights reported, and residents of Damascus, Aleppo and Homs confirmed that Internet, cellphones and land-line phones were all functioning in their areas.

Communications services appeared to have been restored as unexpectedly as they were cut on Thursday, activists said. After the blackout took effect, many activists and ordinary Syrians had feared that the government was planning a new offensive against civilians.

The Syrian government denied any role in the communications shutdown, and the precise cause of the blackout remained unclear Saturday.

Despite the blackout, rebel forces have continued to engage in heavy clashes with government forces in recent days in a push to take over the main commercial airport in the capital, according to activists.

Interactive: Recent events in Syria

Over the past week, rebel fighters have made notable gains, capturing at least half a dozen military bases around the country.

On Saturday, the fighting was concentrated only a few miles from the airport, and Syrian military jets pounded rebel positions in the vicinity with bombs, activists said.

“The airport is one of the most vital targets that the opposition has targeted,” said Ibrahim Sharqieh, deputy director of the Brookings Doha Center. “It can have an impact on the entire situation. This is a very alarming development for the regime.”

State television announced around noon that the airport was open. The facility had been closed Thursday because of the fighting but was reopened Friday afternoon.

For many Syrians outside the country, the difficulty of reaching family members caused great anxiety during the blackout.

“Are they home? Did they take refuge in a different house? I can’t really tell anymore,” said Hussam, a 29-year-old Syrian from Aleppo who lives in Minnesota and asked to be identified only by his first name for the safety of his family in Syria. “How can one man decide to isolate 23 million people from the rest of the world? I would never understand.”

Hussam said he stayed up for two nights in a row trying to reach his family. “I spent last night reading the names of the martyrs in Aleppo, even though I knew they died far away from my neighborhood,” he said. “I was reading and panicking that I might read a familiar name.”

A look at the Syrian uprising nearly two years later. Thousands of Syrians have died and President Bashar al-Assad remains in power, despite numerous calls by the international community for him to step down.

As the fighting continued Saturday, U.N. Secretary General Ban Ki-moon said the conflict in Syria had reached “appalling heights of brutality.” He also warned that the number of refugees from the conflict could reach 700,000 by early next year.

Human rights groups say that at least 30,000 people have been killed in Syria since the uprising began last year.