MOSCOW - The suicide bomber who killed 35 people at Moscow's busiest airport was deliberately targeting foreigners, investigators say, which would mark an ominous new tactic by separatist militants in southern Russia if he was recruited by an Islamist terror cell.

Federal investigators said on Saturday they know the identity of the bomber, a 20-year-old native of the volatile Caucasus region, where Islamist insurgents have been battling for years for a breakaway state.

But the country's top investigative body stopped short of naming him, fearing that it would compromise ongoing attempts to identify and arrest the masterminds of the Domodedovo Airport attack on Jan 24. The blast also wounded 180 people.

There has been no claim of responsibility, but security analysts suspect Islamist separatists of organizing the bombing because of its magnitude and method.

"It was no accident that the terrorist act was carried out in the international arrivals hall," federal investigators said in a statement. "The terrorist act was aimed first and foremost at foreign citizens."

The victims were mainly Russians, but also included one person each from Britain, Germany, Austria, Ukraine, Tajikistan, Kyrgyzstan and Uzbekistan.

The violence stemming from the predominantly Muslim Caucasus region originates from two separatist wars in Chechnya in the past 15 years. Federal forces wiped out the large-scale resistance, driving the insurgency into the mountains and into neighboring provinces. The rebels seek an independent Caucasus emirate that adheres to Shariah law.

Caucasus rebels have claimed responsibility for a number of deadly attacks over the years, including a double suicide bombing on the capital's subway system in March 2010 that killed 40 people. One of the subway stations hit was under the Federal Security Service headquarters in downtown Moscow. The service, the main successor to the feared Soviet KGB, is known by its Russian language acronym, the FSB. The terrorists are out to show that it's not just the Russian public who are defenseless, said Pavel Felgenhauer, an independent security analyst.

"There is always a message," he said. "If the message with the metro bombings was to show the FSB that they are not out of reach, then the message here is that foreigners should keep away from Russia, it's a dangerous place. The point was to scare off foreigners, not to maybe kill them but to hit Russia's image, (and) its economy as an investment destination."

"Looking at Medvedev's reaction, it seems that point got through," Felgenhauer said, referring to President Dmitry Medvedev, who postponed his trip to the World Economic Forum in Davos. When he eventually arrived on Wednesday, Medvedev condemned the perpetrators and sternly defended Russia as an investment haven.

Since the blast at Domodedovo Airport, a half-dozen transport and police officials have been fired. Medvedev said after the blast that Domodedovo's security was in a "state of anarchy."

Russia's parliament has given preliminary approval to a law creating color-coded terrorist threat alerts, a measure rushed forward in the wake of the airport bombing. The proposed law is modeled on the US system instituted after the Sept 11 attacks, which Washington announced on Thursday it would be abandoning by the end of April and replaced with a new plan to notify specific threats. Critics had complained the general color alerts were unhelpful. Russia's State Duma, or lower house, unanimously approved the bill on Friday in the first of three required readings.

Associated Press