The wife of a British human rights researcher believed to have been detained in Qatar has called on David Cameron to demand a response from the Gulf emirate.

Krishna Upadhyaya and Ghimire Gundev have now been missing for almost a week after visiting Qatar to investigate the treatment of Nepalese migrant workers. The Qatari government has yet to make a public statement about their whereabouts.

Now Sarita Poudyal, the wife of Upadhyaya, has said it is time for the British prime minister to intervene.

"The British embassy are pressuring them, but I think it's better to do more," Poudyal told VICE News. "Our government should do more. The prime minister should do more. I think the prime minister should intervene."

Poudyal added: "The Qatari authorities must take immediate action to release him safely and respectfully. They need to give us a proper reason why he has been arrested."

Krishna Upadhyaya, 52, and Ghimire Gundev, 36, failed to board their August 31 flight out of Qatar. Upadhyaya previously sent an urgent text to a friend in Norway saying: "I am being followed by the police here. Looks like they will give me troubles now."

The Qatar embassy in London has not responded to requests for information from VICE News.

The Global Network for Rights and Development, the human rights organization that employed the researchers, told the Guardian they received a "polite and diplomatic" response from Qatar's Ministry of foreign affairs, but the whereabouts of the men is still unknown.

On Friday afternoon around 20 protesters, including representatives from Amnesty International, Prospect and Anti-Slavery International, assembled outside Qatar's embassy in London to hand a letter to Qatari authorities demanding news on Upadhyaya and Gundhev's whereabouts.

"They need to tell us about their condition, where they are and why they have been arrested," Poudyal said. "We really need to know about this, because they were just doing their job. It's very upsetting."

Poudyal and Upadhyaya, who are both British citizens of Nepalese origin, have been married for more than 20 years and live in Wembley. They have a son named Kushal, who is 19, and a daughter called Garima, who is eight.

"My daughter, I don't want her to have mental problems, so at first I didn't tell her, Poudyal said. "But she saw it on the television and she was shocked and she was really crying. She said, 'I miss my dad and I want him to come.'

"She cannot focus anymore. She used to play normally but she's different now."

Poudyal and Upadhyaya met in Nepal. Poudyal said: "He used to come to my sister's house and we met there. He seemed a good, gentle man.

"I kept calling him and finally he called me to say that he's going to catch his flight to go to Norway, but the police were around him and he was not sure he was going to be safe."

"He's a very soft kind person, a lovely person. He's a very genuine person, and that's why I like him."

Upadhyaya moved to Britain in 2002 to take up a post with Anti-Slavery International, which he held until 2013. Since then he has worked for GNRD.

Poudyal last spoke to her husband on August 31. "That is the day he was supposed to leave Qatar to go to Norway," she said. "He was in a hotel and lots of police were around him and watching.

"His friend called me to tell me," She continued. "After that I kept calling him and finally he called me to say that he's going to catch his flight to go to Norway, but the police were around him and he was not sure he was going to be safe."

Poudyal added: "I know he was doing the right thing. My heart is strong for that. He knows his job and he's doing the right thing."

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