There has been a surge of migrant workers leaving Russia for Tajikistan after a Mar 22 concert hall attack near Moscow which left dozens dead, according to Tajikistan's Ministry of Labour, Migration and Employment.

Gunmen opened fire with automatic weapons at concertgoers over a week ago in the worst attack in Russia in two decades which left at least 144 people dead.

Four of the suspected gunmen are Tajik citizens and were arrested along with seven other suspects, some of whom also come from the ex-Soviet Central Asian nation.

"We receive a lot of calls. These are most likely not complaints about harassment, but fear of our citizens, panic, many want to leave. We are now monitoring the situation, we have more people coming (to Tajikistan) than leaving," Shakhnoza Nodiri, deputy head of the ministry, was quoted by Russian state news agency TASS as saying.

Tajikistan detained nine people this week suspected of having links to the mass shooting and also to the militant Islamist State group that claimed responsibility, a Tajik security source said.

A labour shortage in Russia's economy may become even worse due to the outflow of migrant workers, with a deficit in the construction industry growing by 36% this year compared to 2022, Anton Glushkov, president of the National Association of Builders (NOSTROY), told Interfax news agency on Friday.

The Russian Central Bank has said that staff shortages and resulting jump in wages were among risks to inflation that have compelled it to keep the key interest rate elevated.

Tajikistan's labour ministry expects that the outflow of migrants from Russia will be temporary.

According to the ministry's website, 652,014 labour migrants left the country in 2023 compared to 775,578 in 2022.