Misrata, Libya (CNN) -- Russian President Dmitry Medvedev sent an envoy to Libya Monday to meet with rebels trying to bring about an end to Moammar Gadhafi's 42-year-rule, a move that comes after he called for the Libyan leader to step down.
Mikhail Margelov, the presidential special envoy on Africa, was expected to meet with leaders of the rebel Transitional National Council based in the eastern Libyan rebel-stronghold of Benghazi, his spokeswoman, Varvara Paal, said.
Margelov did not rule out traveling to Tripoli to meet with Gadhafi, Paal said.
"My task is to meet with rebel leaders. However, I do not rule out that I may have to go to Tripoli, too, if I get the corresponding order from the president," Margelov told Interfax, the Russian news agency.
Last month, Medvedev joined American and other European leaders in calling for Gadhafi to step down from power. The chief prosecutor for the International Criminal Court has issued arrest warrants against Gadhafi, his son and Libya's intelligence chief for alleged crimes against humanity.
Meanwhile, on Monday, the Swiss government authorized the state's attorney general to open a criminal investigation into the kidnappings of two of its citizens, Rachid Hamdani and Max Goeldi, who allegedly have been held hostage in Libya for nearly two years.
The developments came as rebels on the front line in Misrata said the main station supplying electricity to the city, which had been targeted by Gadhafi forces, had been hit. The attack left some areas of the city without power.
According to various rebel fighters, Gadhafi's forces carried out an early morning offensive on both the western and eastern fronts of Misrata.
Government forces pushed 2 kilometers (1.25 miles) into the city of Dafniya on the west side of Misrata and fired dozens of Grad rockets, destroying a plastic factory which killed one person and injured at least one other.
Rebel fighters were able to stop the attacks and pushed toward the west 3 kilometers (1.9 miles) to the outskirts of the city of Zlitan, rebels said.
Two people were killed and 17 others were wounded in the fighting on the western front of Misrata, rebels said.
Libya has been in the throes of a civil war for months, since Gadhafi dug in his heels against popular efforts to force him out of power amid anti-government protests sweeping the Arab world.
NATO is operating under a U.N. Security Council resolution authorizing the use of any means -- with the exception of foreign occupation -- to protect civilians from attack or the threat of attack. It has been conducting airstrikes targeting Gadhafi's military resources.
Moscow has been a strong critic of the NATO-led mission in Libya, arguing that the scope of the organization's air campaign against Gadhafi's forces far exceeds the civilian protection mandate approved by the U.N. Security Council.
But NATO Secretary-General Anders Fogh Rasmussen said Monday its mission has "made considerable progress."
"We have turned the tide of terror unleashed by the Gadhafi regime, we have saved countless lives and we have seriously degraded the ability of the Gadhafi regime to attack civilians, and we have relieved the pressure on cities, such as Misrata," he said.
Since NATO first took action just over two months ago, "we have kept up a high operational tempo, with over 10,000 sorties," Rasmussen said. "We have damaged or destroyed almost 1,800 legitimate military targets. That includes around 100 command-and-control sites -- which Gadhafi used to organize attacks on civilians."
Gadhafi "has lost his grip over much of the country," Rasmussen said. But he added that the regime "still poses a threat. Last week, the United Nations commission of inquiry reported that his forces have committed widespread and systematic war crimes and crimes against humanity, including murder, torture, persecution and sexual abuse.
"It is an appalling catalogue of crimes. And those very same forces are still launching indiscriminate and illegal attacks against cities such as Zintan," Rasmussen said, referring to the shelling of the city in Libya's western mountains, near southern Tunisia.
"That's why we agreed to extend our mission by a further 90 days," Rasmussen said. "We have intensified our military pressure and we are determined to continue our operation for as long as it takes."
CNN's Maxim Tkachenko and Amir Ahmed contributed to this report.