New attacks in the Middle East on Friday threatened to unravel an already fragile US-Iran ceasefire, even as American officials confirmed that Tehran's football players had received visas for the World Cup.

Weeks of complex talks marked by threats and flare-ups of violence have failed to secure a deal to end the war and reopen the Strait of Hormuz, a key conduit for global energy flows.

A ceasefire in the Middle East war, triggered nearly 100 days ago by US and Israeli strikes that wiped out Iran's top leadership, has been in place since April 8.