Barack Obama speaks to Francois Hollande, offers help in terror attack probe

Washington: US President Barack Obama Friday spoke with his French counterpart Francois Hollande and offered "significant security cooperation" in the probe into the terror attack in Nice as he condoled the loss of innocent lives in the carnage.

"President Obama had an opportunity earlier today to telephone President Hollande and relay his condolences to the people of France on behalf of the American people," White House Press Secretary Josh Earnest told reporters.

"France is after all our oldest ally. So it should be no surprise that President Obama didn't just offer condolences, he offered significant security cooperation and any assistance that they need to conduct their investigation and to take steps to try to prevent something like this from happening again," Earnest said.

In addition to this, Obama's top counter-terrorism adviser, Lisa Monaco, telephoned her counterpart today and US Defense Secretary Defense Ash Carter was also in touch with his French counterpart.

US Secretary of Homeland Security Jeh Johnson has been in touch with the French ambassador to the United States.

"A range of US officials, and law enforcement, and intelligence community and a variety of homeland security agencies have been in touch with their French counterparts to discuss the situation and to pledge a cooperation. So this is obviously something that the US government will be monitoring closely in the days ahead. And we will be offering our strongest support to the people of France in this very difficult time," Earnest said.

A truck driven by a Tunisian rammed into a crowd killing more than 80 people in Nice, France, last night.

France has described this as an act of terrorism.

"There's more about this individual that French authorities have identified as the perpetrator. There's more that needs to be learned about his background, about other people that he may have associated with; anything that would provide some insight into how the attack was planned, how was carried out, and whether or not he received any instruction or direction about doing so," Earnest said.

"We are in the early stages the investigation, but as French authorities begin to collect the information that could help answer those questions, they'll be able to rely on the strong support and the capabilities of the United States government," he said.

Meanwhile, Obama in a proclamation ordered that all US flags be flown at half-staff at White House and other federal buildings.

Earnest said French investigators are still looking very closely at what sort of connections this individual may have to extremist organisations.

"There been no claims of responsibility that we have seen thus far, but we'll obviously look to that as a potential clue about what may have contributed to this particular terrorist attack. But at this point it's too early to draw any firm conclusions about whether or not this individual had ties to a broader terrorist network, or was part of a broader terrorist conspiracy," he said in response to a question.