According to Afghan and Norwegian media, the talks were expected to focus on women's rights in Afghanistan.
"We can confirm that Norway is hosting informal discussions with a number of Afghans from varied political backgrounds. The participants include a number of political officials and members of civil society, including women and members of the Taliban," foreign ministry spokesman Frode Andersen told AFP.
"The participants are all here as individuals (and not as representatives of parties) and are expressing their personal opinions. The discussions have no official status and these are not negotiations," he added.
But informal talks, mostly involving Afghan lawmakers and civil society activists, have occurred in the recent past under a veil of secrecy even as the Taliban intensify their annual spring offensive.
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In last month's informal talks in Qatar, the Taliban, condemned for their misogynistic ideology and lack of respect for human rights, pledged support for women's education and their right to work in "male-dominated professions", activists said.
Several other meetings have taken place in the past, including in Norway. But this time, the Afghan delegation is made up of mostly women, according to Afghan television 1TV.
But the HPC officially distanced itself from the talks in Norway.
"We are not aware of any meetings in Norway," senior HPC member Ismael Qasimyar told AFP, declining to comment further.
Koofi and Nuristani were out of the country, their private secretaries told AFP, without confirming if they were in Norway.
"However, the issue of women's rights and their role in peace process and after negotiations are most likely.