Jackson has not been seen in public since being acquitted

Joe Jackson - who turns 76 on Friday - said he hoped his son would join the celebrations, but that he could not confirm rumours he would attend.

It would be the first time Jackson has appeared in public since he was cleared of child sex charges last month.

"I hope that Michael will come to Berlin. We have a lot of fans in Europe," Joe Jackson said.

Open invitation

"They were in Santa Maria to support the family. It's about the European fans, those who care about the family."

Jackson, 46, threw open the invitation to 1,000 friends and fans to attend the party at the Estrel hotel.

His brothers and sisters - Jermaine, Janet and LaToya - are expected to be there, while a spokeswoman for the hotel said she was "70% sure" Jackson himself would be present.

"We hope he will come, everything is ready," said Mihaela Djuranovi.

"We are waiting for him. All he needs to do is get on a plane."