(L-R) US Secretary of State John Kerry, European Union Foreign Policy Chief Catherine Ashton, and Iran's Foreign Minister Mohammad Javad Zarif are photographed as they participate in a trilateral meeting in Vienna October 15, 2014. [Photo/Agencies]

VIENNA - A senior US official said after high-level nuclear talks with Iran on Wednesday that some progress continued to be made but much work remained to be done, adding the goal was still to reach a deal by a late November deadline.

The State Department official spoke after about six hours of talks between US Secretary of State John Kerry, Iranian Foreign Minister Mohammad Javad Zarif and European Union foreign policy chief Catherine Ashton in Vienna.

"We've been chipping away at some of the issues. Everybody has put ideas on the table to see if we can move the ball forward," the official said. "We have and continue to make some progress but there's a substantial amount of work to be done."

Iran and six world powers - the United States, France, Germany, China, Russia and Britain - aim to end a decade-old nuclear standoff by a self-imposed Nov 24 deadline. 

A new round of talks, to be attended by negotiators from the P5+1 group and Iran, will begin on Thursday in Vienna.

In the previous round of talks held in New York in September, Iran and the world's major countries failed to make big progress, prompting some people to doubt if the negotiators could find a solution to address the remaining tough issues in the six weeks ahead of the deadline.

Zarif told Iranian media on Tuesday that the negotiators might need more time to address the remaining concerns.

Also on Tuesday, the United States State Department spokeswoman Jennifer Psaki said the US was still exploring the possibility of reaching a comprehensive deal over Iran's nuclear program by the deadline next month.

In November last year, relevant sides agreed on an interim deal and planned to reach a comprehensive accord on July 20. Under the deal, Iran suspended sensitive nuclear activities in exchange for limited sanction relief.

In July, Iran and the six major countries agreed to extend negotiations for another four months till Nov. 24, as they were unable to narrow down significant gaps on core issues over the previous six months.

Western states have long suspected Iran of developing nuclear bombs under the cover of Tehran's civilian nuclear program. Iran has rejected the allegation, saying its atomic plan is exclusively peaceful.