The Taliban have arrested two Afghan journalists working for a local news channel, rights groups and the United Nations said Tuesday, weeks after two women activists went missing.

Since seizing power in August, the hardline Islamists have cracked down on dissent by detaining critics and forcefully dispersing protests against their regime.

Several Afghan journalists have also been beaten while covering rallies not approved by authorities.

The Afghan Media Association -- a newly formed journalists' rights group -- said Ariana TV reporters Waris Hasrat and Aslam Hijab were picked up by the Taliban on Monday "and taken to an unknown location".

Without naming the Taliban, an official at Ariana told AFP the reporters were seized by masked gunmen in front of the channel's office as they went out for lunch.

But he said Taliban officials "have assured us of a comprehensive investigation".

The United Nations Assistance Mission in Afghanistan (UNAMA) also expressed concern over their whereabouts.

"UN urges Taliban to make public why they detained these ArianaNews reporters and to respect Afghans' rights," it said on Twitter.

Amnesty International, meanwhile, demanded on Twitter that the Taliban "unconditionally and immediately" release the pair.

A Taliban spokesman told AFP he had no information on the missing journalists.

Missing women

A fortnight ago, two women activists went missing after taking part in a demonstration in Kabul calling for women's rights.

On Tuesday the UN High Commissioner for Human Rights expressed concern for them and four of their relatives, who are also missing.

The Taliban denied knowledge of their whereabouts, and say they are investigating.

The UN said it was alarmed by what appeared to be a "pattern of arbitrary arrests... as well as torture and ill-treatment" of civil society activists, journalists and members of former government and security forces.

A UN report this week accused the Taliban and their allies of killing more than 100 security and civilian personnel linked to the former US-backed government since returning to power.

Taliban officials have rejected the claims.

Last month, the Taliban detained a well-known university lecturer and regime critic Faizullah Jalal but released him days later after a media furore in Afghanistan and abroad.

Despite promising their second time in power would feature a softer brand of governance, the Taliban have slowly introduced restrictions on freedoms -- especially for women.

Western countries insist the Taliban must respect women's rights to unlock billions of dollars in assets and foreign aid.

The halting of aid has triggered a catastrophic humanitarian crisis in a country already devastated by decades of war.