CAIRO – An Egyptian presidential candidate who was the last prime minister in the regime deposed by last year’s popular revolution lashed out at his Islamist rival Sunday, warning he and his fundamentalist group would monopolize power and take Egypt back to “the dark ages.”

It was a sign that the runoff race between Ahmed Shafiq, the ex-premier, and the Muslim Brotherhood’s Mohammed Morsi was turning into a bitter contest over who could make his rival seem more frightening to voters. The two face off in a June 16-17 vote.

“I represent the civil state,” Shafiq told a news conference. “The Brotherhood represents darkness and secrecy. No one knows who they are or what they are doing. I represent dialogue and tolerance.”

“They want to monopolize power,” he said. “They don’t want to take us 30 years back, but all the way back to the dark ages.”

Morsi, for his part, has tried to cash on the unpopularity of a court verdict that sentenced deposed President Hosni Mubarak to life but acquitted him and his two sons of corruption. Six top police commanders accused of complicity in the killing of protesters during last year’s uprising were also acquitted.

Tens of thousands demonstrated Saturday in Cairo’s Tahrir Square, birthplace of last year’s uprising that toppled Mubarak’s regime, and in other cities to protest against the verdict. Several thousand were in Tahrir Square again on Sunday, and the number was steadily increasing as the afternoon heat wore off.

Morsi has been warning of a Mubarak-style crackdown on opponents if Shafiq is elected. Supporters of the Brotherhood, which had until Mubarak’s ouster last year been outlawed for nearly 60 years, were harassed and imprisoned during the former president’s 29-year rule.

Morsi went to Tahrir Square on Saturday night to show solidarity with the protesters and scheduled a meeting later Sunday with families of some who were killed. He also vowed to retry Mubarak, his sons and aides, promising not to rest until the dead protesters are avenged.

Shafiq questioned whether Morsi would be the actual president, or rather a front for the Brotherhood’s real spiritual and political leaders.

“Would the president of Egypt be the one who was elected, or there would be another one behind the scene?” Shafiq asked. Countering charges that he was an extension of the deposed Mubarak regime, he said the Brotherhood made several deals with the old regime and its security agencies.

“How come you flirt with the (minority Christian) Copts in news conferences and later harass them in their homes and businesses?” he asked.