Six of the new suspects used British passports
Police in Dubai have identified 15 more suspects in last month's killing of a senior member of Palestinian militant group Hamas, taking the total to 26.
Six of the new suspects involved in the death of Mahmoud al-Mabhouh had UK passports, while the rest had Irish, Australian and French documents.
Many had allegedly used credit cards issued by a small US-based bank.
On Tuesday, Israeli opposition leader Tzipi Livni applauded the killing, which Dubai believes Israel was behind.
Israel has repeatedly refused to confirm or deny its involvement.
One of the founders of Hamas's military wing, the Izz al-Din Qassam Brigades, Mr Mabhouh was found dead in a hotel room in the Gulf emirate on 20 January.
A post-mortem examination report said he had been electrocuted and then suffocated.
Earlier this month, the Dubai authorities released the names and passport photographs of 11 "agents with European passports" - six from the UK, three Irish, one French and one German.
All four countries have since said the documents were fraudulent.
On Wednesday, the police released a new list of suspects who allegedly offered "logistical support" in the months before the January killing.
They include 10 men and five women travelling on British, French, Irish and - for the first time - Australian passports.
The police also produced a chart tracing the travel routes of both the new and old suspects before and after Mr Mabhouh's death.
"The suspects gathered in Dubai and dispersed to various locations before pairing up again in different teams and heading off to other destinations," they said.
In a new development, the police said two of the Australian passport holders had allegedly travelled by boat to Iran during a reconnaissance mission last August.
Investigators have also discovered that 14 of the suspects had used credit cards issued by MetaBank - a small bank based in the US state of Iowa - to book hotel rooms and pay for air travel.
A MetaBank spokeswoman told AP news agency that the bank was trying to confirm the reports.
The six newly identified suspects who used UK passports were listed as Daniel Marc Schnur, Gabriella Barney, Roy Allan Cannon, Stephen Keith Drake, Mark Sklur and Philip Carr.
Mr Mabhouh died in his hotel room in Dubai last month
Those on Irish passports were Ivy Brinton, Anna Shuana Clasby and Chester Halvey; on French passports David Bernard LaPierre, Melenie Heard and Eric Rassineux; and on Australian passports Bruce Joshua Daniel, Nicole Sandra Mccabe and Adam Korman, according to the statement.
British officials said they were trying to contact the people whose names and passport details had been used.
"We can confirm that six more UK passports have been identified," the Foreign Office in London said. "We will seek to make contact with these individuals and offer consular assistance as we have the previous individuals."
"The foreign secretary and others have made clear we expect full Israeli co-operation," it added.
The Dubai police statement said the investigation was ongoing and that they were "not ruling out the possibility" of more suspects.