A pregnant Russian human rights researcher said Thursday she had received anonymous text messages threatening her life and that of her child, which she believes are linked to her work in the troubled North Caucasus region.

Tanya Lokshina of Human Rights Watch said she suspected that security officials were bugging her telephone and making the threats after she arranged a business trip to Dagestan, a mostly Muslim province of North Caucasus, last week. The unknown authors wrote she would go through "an uneasy 'birth'" and vowed to come after her in Moscow.

The Russian Interior Ministry said it had received a request from Russia's rights ombudsman to investigate Lokshina's claims and would conduct the probe.

Lokshina said the messages contained information that would be impossible to know without security services involvement, such as her due date, her unregistered home address and her relatives' travel plans.

Activists and independent journalists who worked in the volatile North Caucasus region frequently faced kidnapping, threats and even death.

Journalist Anna Politkovskaya, a fierce critic of the Kremlin and its policy of Chechnya, was gunned down in the elevator of her Moscow apartment building in 2006, and activist Natalya Estemirova, who collected evidence of rights abuses by security forces in Chechnya, was abducted in 2009 and found shot dead the same day.

And last December, Khadzhimurad Kamalov, the founder of a newspaper critical of authorities in Dagestan that reported extensively on police abuses was gunned down outside his office.

Lokshina is one of the leading experts on the North Caucasus, helping expose human rights abuses. Vowing to continue her work undeterred, she blamed the threats on the atmosphere created by new Kremlin restrictions on non-government organizations' activities, which she described as "the worst in 20 years."

Since Vladimir Putin's inauguration for a third presidential term in May, the Kremlin-controlled parliament has passed a series of repressive laws, including the one that required the NGOs receiving funding from abroad to register as "foreign agents." Putin has frequently accused nonprofits of acting as proxies for the U.S. to meddle in Russian domestic affairs.