CAIRO - US Secretary of State Rex Tillerson said Monday it was "too early" to discuss direct negotiations with North Korea, after Vice President Mike Pence said the US was open to talks.

Pence was quoted in the Washington Post on Sunday as saying the US and South Korea had agreed terms for future diplomatic engagement with North Korea. He said the United States and its allies would impose "steep and escalating costs" on Pyongyang until it takes "clear steps toward denuclearisation". But he said the White House was willing to "sit down and talk with the regime while that pressure campaign is ongoing". "If you want to talk, we'll talk," the paper quoted him as saying.

Asked about the article during a visit to Egypt, Tillerson said: "I think it's too early to judge."

"We've said for some time it's really up to the North Koreans to decide when they're ready to engage with us in a sincere way, a meaningful way," he said. "They know what has to be on the table for conversations."

He said it was important first "to determine whether the parties are in fact ready to engage in something that's meaningful."

President Donald Trump and North Korean leader Kim Jong Un have exchanged a series of personal insults. Pence's comments come at a time of reconciliation between the two Koreas, which are still technically at war.

North Korean leader Kim Jong Un has used the Winter Olympics hosted by South Korea to unleash a diplomatic charm offensive.

But Pence, speaking to reporters on Saturday, stressed "the need to continue to isolate North Korea economically and diplomatically until they abandon their nuclear and ballistic missile program."

Rex Tillerson held talks Monday in Cairo with Egyptian President Abdel Fattah al-Sisi and Foreign Minister Sameh Shoukry at the start of a Middle East tour. Tillerson landed in Cairo late Sunday and had dinner with Shoukry. On Monday morning, the two foreign ministers met behind closed doors and then addressed reporters, and later Tillerson had talks with Sisi before heading to the airport on route to Kuwait.

Tillerson's visit comes as Sisi, who has been president since 2014, looks set to be re-elected next month in polls in which he will face a single opponent.

All serious potential presidential contenders have either been jailed or withdrew, with some claiming the entire process was not conducive to free elections.

Speaking about the polls due to be held March 26 - 28, Tillerson told reporters that Washington supports "a transparent credible electoral process".

"We have always advocated free, transparent, fair elections, not just in Egypt but in any country," he said in response to a question on whether the elections would be considered credible, free or fair.

Tillerson's trip to Cairo comes after Vice President Mike Pence visited last month to discuss security in the region and the future of US aid to Egypt.

However, Tillerson did not respond to a question on whether the US would freeze part of its military aid to Egypt if the elections were deemed not credible.

"On the elections, we support a genuine and a credible electoral process, and we believe should guarantee the right for all citizens to participate freely and fairly," a US State Department official said ahead of Tillerson's visit.

The same official, however, mentioned "concerns about human rights and civil society" as "a topic of continuing conversation with the Egyptians."

"We have noted our concerns about the reports that Egypt's prosecutor general has launched an investigation into opposition figures ahead of the" vote, he added.

Right groups accuse the Egyptian government of arbitrary arrests and enforced disappearances of dissidents, which spiked after the military overthrew Islamist president Mohamed Morsi in 2013 and cracked down on his supporters.

Asked to comment about Egypt's human rights record, Shoukry told reporters they should see for themselves "the nature of the current situation in Egypt" and "how the the Egyptian people view this administration and its efforts to strengthen and protect human rights and whether there is this sense of restriction that you allude to."

Tillerson said he also discussed with Shoukry a joint commitment by the United States and Egypt to defeat the Islamic State group, adding that their joint efforts are "steadfast".

They also discussed the Israeli-Palestinian peace process and Tillerson said the US administration "remains committed to achieving a peace agreement between Israelis and the Palestinians". He did not elaborate.

US President Donald Trump announced in December his decision to recognise Jerusalem as the capital of Israel and said he would move the US embassy there from Tel Aviv, sparking fury in Arab and Muslim countries.

On Syria's nearly seven-year war, Tillerson reiterated that the conflict can only be resolved through a UN-sponsored political framework.

After Cairo, Tillerson is to head to Kuwait to take part in a ministerial meeting of the US-led military coalition that has been battling the Islamic State militant group in Iraq and neighbouring Syria.

He is also set to visit Jordan to meet King Abdullah II and Lebanon to meet President Michel Aoun and Prime Minister Saad Hariri. He is then set to head to Turkey for discussions with Washington's NATO ally including on the conflict in Syria.