Superintendent Rodelio Jocson, San Juan police chief, said the deployment of additional policemen was requested by Sandiganbayan sheriff Ed Urieta.
Jocson said the Police Security and Protection Office (PSPO) of the Philippine National Police (PNP) has the lead role in securing Estrada during his nine-hour furlough.
The Sandiganbayan granted on Friday Estradas request for a furlough to allow him to spend Christmas with his family.
But the furlough was only for nine hours, and not the four-day pass as he had requested.
The short stay with his family drew protest from Estradas spokesman Rufus Rodriguez, who was hoping for a long furlough "in the spirit of the holiday season."
Jocson explained that like in Estradas previous furloughs, the San Juan police will deploy additional policemen for his security.
"We will be posted in areas where the PSPO would like us to be," said Jocson, as he refused to reveal where Estrada and his family will spend Christmas.
He said San Juan has been relatively peaceful as of yesterday and he sees no problem with Estradas presence in San Juan, where he was once mayor.
Other San Juan police units will remain on standby, ready to reinforce Estradas security if necessary, Jocson added.