ALMATY (Reuters) - Opposition politicians and activists in Tajikistan have accused the government of orchestrating lynch mob-style attacks on their families as part of a broader crackdown on dissent by President Imomali Rakhmon.

The Dushanbe government has denied directing the attacks and said it would investigate them.

Tajik authorities last year outlawed the opposition group, the Islamic Renaissance Party of Tajikistan (IRPT), and have since jailed most of its senior officials on charges of staging a failed September 2015 coup.

Now, politicians say, their families are being targeted by mobs acting with impunity.

"Threats, pogroms, arsons and stone-throwing attacks have begun against the homes of the relatives of opposition members and those who have spoken at this conference," Mukhiddin Kabiri, the leader in exile of IRPT, told a conference of the Organization for Security and Cooperation in Europe in Warsaw on Wednesday.

Kabiri, who addressed the conference by Skype, said there had been at least six such attacks across the Central Asian state over the preceding three days, including those against his relatives.

U.S.-based rights group Human Rights Watch also cited several cases of mob attacks, in one of which the crowd assaulted a 10-year-old niece of a political activist, hitting and kicking her.

Circumstances "suggest that the attacks were orchestrated and coordinated by Tajik authorities", the group said.

"Tajikistan is in the midst of the worst political and religious crackdown since the end of the country’s 1992-1997 civil war."

The official Tajik delegation had walked out of the same conference on September 23, protesting that the OSCE had allowed opposition activists to take part and describing them as criminals.

Tajikistan's Interior Ministry said on Thursday it had not received any requests from the alleged victims of the attacks but would investigate them.

President Rakhmon enjoys sweeping powers amid a flourishing personality cult, and strengthened his position even further this year through a referendum that amended the constitution, allowing him to run for an unlimited number of terms.

Mostly Muslim Tajikistan, which borders volatile Afghanistan, is the poorest former Soviet republic with per capita gross domestic product of just $2,780, according to World Bank data. Almost one-third of the population officially lives in poverty.

(Reporting by Olzhas Auyezov; Editing by Richasrd Balmforth)