Bana Alabed and her family had attracted worldwide attention for their tweets from war torn Aleppo.
But now the account appears to no longer exist.
Although it's no longer possible to see any of her messages, reports suggest her last post read: "We are sure the army is capturing us now. We will see each other another day dear world."
The tweet was signed by Bana's mother Fatemah.
The phrase #WhereIsBana has been trending on social media ever since her account was suspended and people became concerned.
On Friday, JK Rowling shared a video of Bana.
In it she tells viewers she is "on the run" and asks for people to "please save us".
The Harry Potter author sent a digital copy of one of her the novels to Bana last month, after Fatemah said her daughter had seen the movies and liked them.
Bana said she read "to forget the war".
Last week the family shared images of the aftermath of their home being bombed.
Bana was pictured covered in dust.
Big parts of east Aleppo, held by rebels, have been seized by government troops and militiamen in the past three weeks.
Around 250,000 people are trapped in parts of the city caught up in the conflict.
Thousands of people have been displaced.
The situation has become so bad that operations are being carried out without anaesthetic.