July 24 (Reuters) - Iran on Saturday dismissed as meddling in its internal affairs criticism by the United Nations" human rights boss of the shooting deaths of protesters during demonstrations over water shortages. Meanwhile, rallies in support of the protests in the southwestern province of Khuzestan spread to the northwest of the country on Saturday, according to videos posted on social media. U.N. High Commissioner for Human Rights Michelle Bachelet on Friday expressed concern about deaths and injuries and widespread detentions over the past week in oil-rich Khuzestan. Iran"s Foreign Ministry spokesman Saeed Khatibzadeh said in a statement carried by Iranian media that Bachelet"s "interventionist" and "non-expert and biased comments on the management of the country"s water resources were not within the scope of commissioner"s responsibilities". In addition to the drought, Khatibzadeh said U.S. sanctions had "prevented the transfer of technology to and investment in Khuzestan"s water sector". Iranians have taken to the streets for more than a week to vent their anger about the shortages which have come during the country"s worst drought in half a century and as the economy creaks under U.S. sanctions and COVID-19. Social media videos on Saturday showed groups of demonstrators chanting slogans in the northwestern city of Tabriz in support of the Khuzestan protesters. Reuters could not verify the footage. Late on Thursday, one youth was shot dead and seven were injured during solidarity demonstrations in the Lorestan province that neighbours Khuzestan, a police official said, blaming "counter-revolutionaries" for the violence. Videos on social media on Friday showed marchers in the city of Aligudarz chanting slogans against Supreme Leader Ali Khamenei. At least one policeman and three young men had been shot dead in earlier protests, according to Iranian officials who blamed "rioters" for the deaths. read more However, Amnesty International said at least eight people had been killed during the unrest. The Human Rights Activists News Agency (HRANA) said on Saturday that it had been able to identify 10 killed and 102 detained. Witnesses spoke of continued heavy security presence in Khuzestan on Saturday. "Mobile internet is still down and there are security forces everywhere," a resident of the provincial capital of Ahvaz, who asked not to be named, told Reuters. Khamenei on Friday called on officials to deal with the crisis, saying people could not be blamed for protesting over water shortages. Mirroring Khamenei"s position, President Hassan Rouhani said on Saturday: "With the exception of a few, people are exercising their legal right to protest."