Tripoli, Libya (CNN) -- Rebels pushed Thursday northward on three fronts toward the coastal cities of al-Zawiya, Aziziya and Sorman, with their ultimate goal being Tripoli, rebel field commander Adel Al-Zintani told CNN.

Six rebels died and dozens more were wounded in fighting Wednesday and Thursday, he said.

He predicted that the fighters would reach the coastal road that leads to the capital city within days.

Zawiya is strategically important because the coastal road through the city is the main supply line from the Tunisian border to areas held by Libyan leader Moammar Gadhafi.

Regime officials were not available Thursday evening for comment.

Fighting was continuing around Misrata, where rebel spokesman Mohamed Ibrahim said the main hospital reported four rebels killed and 54 wounded.

Meanwhile, in New York, a spokesperson for Ban Ki-moon said the U.N. secretary-general "is deeply concerned by reports of the unacceptably large number of civilian casualties as a result of the conflict in Libya."

Ban is urging "all Libyan parties" to engage with his special envoy, Abdel-Elah Al-Khatib, "and respond concretely and positively to the ideas presented to them, in order to end the bloodshed in the country," the spokesperson said.

His remarks came three days after allegations that a NATO strike in the village of Majer near Zlitan wound up killing 85 civilians --- 33 children, 32 women and 20 men.

The Tripoli government called it "a massaacre" of civilians; NATO has said its warplanes struck two farms used as a staging point for Gadhafi's forces

Answer the following questions:
1. What is Ban Ki-moon worried about?
2. Where?
3. What is happening in Libya?
1. Civilian casualties
2. Libya.
3. Conflict.