A Ukrainian journalist, Ankhar Kochneva, continues to be held by Syrian rebels who have reportedly threatened to kill her unless a hefty ransom is paid.

The rebels have given the Ukrainian government more time to meet their demands, the official RIA Novosti news agency reported Tuesday.

And Russian Foreign Minister Sergei Lavrov said Tuesday that Moscow was taking "all the necessary steps" to free two Russian citizens abducted in Syria on Monday, RIA Novosti reported.

Their captors have demanded a ransom payment, the state-run Itar-Tass news agency cited the Foreign Ministry as saying.

The two Russians, who work for a private company in Syria, were seized near the port city of Latakia, Itar-Tass reported. An Italian engineer was kidnapped alongside them.

Blasts shake Palestinian refugee camp in Damascus

Explosions rang out inside a densely populated Palestinian refugee camp in Damascus as clashes erupted again between rebel fighters and a pro-government Palestinian militia, the Syrian Observatory for Human Rights said.

The renewed fighting comes amid wide concern about the humanitarian situation in the Yarmouk refugee camp, home to nearly 150,000 people.

Syrian warplanes bombarded the camp Sunday, hitting a school and a mosque and causing at least 15 deaths, the opposition Local Coordination Committees of Syria said.

Since then, fighting between rebels and a Palestinian faction reportedly led by Ahmad Jibril, a longtime leader of the Popular Front for the Liberation of Palestine General Command, has rocked the camp.

One displaced Yarmouk resident told the pro-Assad Al-Watan newspaper that a large number of Syrian armed forces were gathering to the west of the camp Tuesday.

He said he believes this "may be a lead-up to a military operation to cleanse the camp of the militants."

Mohammad Shtayyeh, a member of the central committee of the Palestine Liberation Organization and head of the relief committee for the Palestinians in Syria, condemned the loss of life in Yarmouk.

He said it was the responsibility of the Syrian government to ensure the safety of Palestinians in their country.

"Palestinian blood should not be part of the struggle for Syria, and the Palestinians are not part of it," he told CNN.

Speaking by phone to U.N Secretary-General Ban Ki-moon on Monday, Syrian Foreign Minister Walid Al-Moallem warned the Palestinian refugees against helping the rebels.

He "stressed the need for the Palestinians to refrain from supporting or harboring these armed group which are intruders to the camp and help expel them," according to Syrian state news agency SANA.

UNRWA, the U.N. agency for the Palestinian refugees, said that "credible reports point to civilian deaths, injuries and destruction of property in Yarmouk."

Thousands are fleeing the camp in search of safety, the agency said. UNRWA is now housing more than 2,600 displaced people in the Damascus area, a number that is rising fast, it said. Initial reports suggest well over 2,000 Palestinian refugees have also sought refuge in Lebanon, it said.

The agency "remains gravely concerned about the safety of the Palestine refugee population in Syria and appeals to all parties to refrain from actions that endanger civilian lives and property," it said.

U.N. humanitarian chief Valerie Amos said via Twitter that she was horrified by the bombing of the camp. "Senseless loss of life. Civilians must not be targeted," she said.

U.S. State Department spokeswoman Victoria Nuland said the latest attacks "mark a significant and alarming escalation of the conflict in Syria. All parties must stop unlawful attacks on civilians and comply with international law."

Palestinian Authority President Mahmoud Abbas has urged combatants in Syria "to spare our camps and our people in Syria" and not draw the Palestinians into the civil war. He also called on the world community "to take immediate action" to protect Palestinians in Syria.

Rebels and the government have gained and sought support from Palestinians in Syria.

Many displaced Palestinians have been living for decades in Yarmouk, a nearly square-mile district inside Damascus about five miles from the center of the city.