Turkish security forces have arrested four people in connection with the suicide bombing in Istanbul in which 10 German tourists were killed, Turkish prime minister Ahmet Davutoglu has said.
Tuesday's blast in Sultanahmet Square killed 10 German tourists and wounded 15.
David Cameron has offered Turkey British assistance to find the organisers of a bomb attack in Istanbul.
At least 10 people were killed and 15 injured in a blast that Turkish president Recep Tayyip Erdogan described as "Syria-linked".
In a telephone call this evening, Mr Cameron offered his condolences to President Erdogan, a spokesperson for Downing Street said.
The Democratic presidential candidate may also have shown his cards on his choice of running mate.
The US president also shared a post on Twitter accusing Dr Anthony Fauci of misleading the public over hydroxychloroquine.
Fears over an impending second wave of coronavirus dominates Wednesday’s front pages.