A Reuters reporter who witnessed the search party's discovery of the abandoned vehicles said they had been extensively damaged.
"If, as has been speculated, the group is being held against their will, it may be they have been the victims of mistaken identity."
Bob Dewar, Britain's ambassador to Ethiopia
"One had eight shrapnel holes in the right-hand doors. The other had a hole that looked like it had been caused by an explosion in its front passenger door," the reporter said.
Representatives from the British foreign office and British embassy staff travelled two days to reach Hamad-Ile.
Several British newspapers, quoting defence sources, said London had sent special forces to Ethiopia to help locate the missing party, but the British ministry of defence would not confirm or deny the reports.
"It is our official position that we do not normally comment on special forces activity and special forces operations in particular," a statement said.
Appeal for information
The Westerners were captured along with 13 Ethiopians working as drivers and translators.
Five Ethiopians were later found close to Ethiopia's border with Eritrea.
"If, as has been speculated, the group is being held against their will, it may be they have been the victims of mistaken identity," said Bob Dewar, Britain's ambassador to Ethiopia.
Dewar called for anyone in the Afar community with information about the kidnapped group to contact the British embassy or Ethiopian authorities.
Eritrea has denied allegations by an Ethiopian official that forces from Arat military training camp in Eritrea made the capture.
On Sunday, Ethiopia, which has strained relations with its neighbour after a 1998-2000 border conflict, said the identity of the kidnappers had yet to be established.