The protest came days after the former autocrat was heard in a leaked audio recording insisting that the tiny West African state guarantee his right to return.
Jammeh ruled Gambia with an iron fist for 22 years, but fled in January 2017 after losing a presidential election to relative unknown Adama Barrow.
Calls for his return from Equatorial Guinea have grown recently as tensions heighten over Barrow’s decision to stay in office for five years — reversing a previous pledge to step down after three.
On Thursday, thousands of supporters of Jammeh’s Alliance for Patriotic Reorientation and Construction (APRC) party gathered in Sukuta, a town 20 kilometres (12 miles) from Banjul, an AFP journalist said.
“We need him one hundred percent. We are ready to die for him,” said 26-year-old protester Ismaila Colley, referring to Jammeh.
“Before Jammeh left here for exile, there was an agreement for him to come back into the country after three years.”
Thousands of Gambians protested last month demanding that Barrow step down, and similar protests are planned for January 19 or 20.
Barrow supporters have also held counter-demonstrations.
The ex-president’s supporters argue he has a right to return under a joint statement from the African Union, the Economic Community of West African States (ECOWAS) and the United Nations, published at the time of his exile.
The organisations committed to working with the Gambian government to ensure Jammeh’s security and rights, in particular his right to return.
Barrow’s cabinet has said that Jammeh can return as a citizen but cannot run for president again.
‘We don’t believe anything’
APRC leaders went to the African Union, ECOWAS and UN offices in Banjul to deliver petitions for Jammeh’s return on Thursday, before addressing their supporters in Sukuta.
“Our message is clear: We want Jammeh to return to The Gambia. He is only one who can rule this country,” APRC deputy leader Ousman Rambo Jatta said.
Yankuba Colley, a party activist, told a chanting crowd of party supporters that Jammeh had to come back “peacefully and unconditionally”.
“We don’t believe anything about the allegations levelled against him,” he said.
The former autocrat is accused of numerous human rights abuses.
Since January 2019, some 190 witnesses have appeared before a Truth, Reconciliation and Reparations Commission (TRRC) set up to investigate abuses under his rule.
There are numerous calls for Jammeh to return to Gambia to face trial, however, others want his return to active politics.
Maimuna Jaju, a 23-year-old businesswoman, told AFP that people were “experiencing hardship” under Barrow.
“This is why we want former President Jammeh to come back and take over the mantle of leadership,” she added.
In the audio recording leaked last week, the ex-president said he supported Thursday’s protest.
“The fact of the matter is to meet the authorities and make it very clear to them that the agreement must be implemented,” Jammeh said in the recording.