Syria's popular Twitter girl Bana Alabed is among many residents in eastern Aleppo sending out what they say are their last messages as they report coming under heavy bombardment from government forces.

Thousands are trapped in rebel-held areas as the forces of President Bashar Al-Assad close in, with many sending out desperate please, says BBC Trending.

Bana has attracted more than 200,000 followers worldwide with her tweets about the siege of Aleppo, with her videos and photos of the effects of the bombings being widely shared.

"My name is Bana, I'm 7 years old. I am talking to the world now live from East #Aleppo. This is my last moment to either live or die. - Bana," she said on Tuesday (Dec 13).

Earlier, she had tweeted that her dad was injured.

And her mother Fatemah, who manages Bana's Twitter account, sent out a tweet on Dec 12 fearing for the family's safety.

But the Alabed family are not the only ones sending out pleas.

"I can tweet now but I might not do it forever. Please save my daughter's life and others. This is a call from a father," tweeted English teacher and activist Abdul Kafi Alhamdo, who was also broadcasting on Periscope on Tuesday (Dec 13).

"I don't know what to say... I hope you can do something for Aleppo people. For my daughter, for the other children," he pleaded.

"You might not understand what we are suffering here... don't believe any more in the United Nations. They are satisfied that we are being killed. That we are facing one of the most difficult or the most serious or the most horrible massacres in history."

In his posts, Mr Alhamdo has tried to explain why he stayed in the area. "Understand this. I can't simply surrender and being captive. I am speaking out and this is a crime," he said.

"At least we know that we were free people. We wanted freedom. We didn't want anything else but freedom."

Syrian troops are on the verge of recapturing all of Aleppo, which the rebels fighting against President Assad first claimed in 2012. The complete fall of eastern Aleppo into government hands would mark a major victory for Assad.

The fall of Aleppo would be the worst rebel defeat since Syria's conflict began in 2011, and leave the government in control of the country's five major cities.

More than 300,000 people have been killed since the conflict began in March 2011, and over half the population has been displaced, with millions becoming refugees.

A US journalist also sent out what he said was his "final message" from eastern Aleppo as gunfire and explosions could be heard in the background.

Writing on Twitter, Bilal Abdul Kareem, a journalist with the On The Ground News website in rebel-held Syria and an occasional contributor to Middle East Eye, said that "regime forces are closing in and bunker busters are raining down", referring to heavy artillery that can penetrate underground shelters.

Lina Shamy, an activist, says on Twitter: "Humans all over the world, don't sleep! You can do something, protest now! Stop the genocide".

Others appear to have given up hope, posting messages as bombs fall around them, says the BBC.

One man says it is the last video he will post. "We are tired of talking, we are tired of speeches. No one listens, no one responds. Here comes the barrel bomb. This is the video's ending." As he signs off, a bomb explodes nearby.

Waking up on Tuesday morning, still alive, Monther Etaky writes: "I still here [sic], facing the genocide with my special friends without any comments from the world."

But the threat of imminent death is still here. "I hope I could broadcast our live death to you," he says bitterly.

The White Helmets - a Syrian volunteer group which has been working in East Aleppo - described the scene on the ground as "hell" in a harrowing message on Monday. "...All streets & destroyed buildings are full with dead bodies".

The United Nations Secretary-General Ban Ki-Moon has said he is alarmed by "reports of atrocities against a large number of civilians" in the area, says BBC Trending.

The UN's humanitarian adviser on Syria, Jan Egeland, has appealled again to Russia and the Syrian government to let it evacuate wounded and other vulnerable groups from Aleppo.