The Home Secretary has pledged her full support to anti-terror officers questioning a Ukrainian man on suspicion of murdering an 82-year-old Asian grandfather.
Theresa May said she was "shocked and sickened" at bomb attacks on three mosques in the West Midlands and the murder of Mohammed Saleem, which are being treated as acts of terrorism.
Ms May said she had asked the officer in charge of the inquiry to keep her informed of any developments in the investigation, which was launched after a home-made device exploded in Walsall on June 22.
Two Ukrainian men, aged 25 and 22, were arrested in Birmingham on Thursday by officers investigating blasts which occurred near mosques in Walsall, Tipton and Wolverhampton.
Police said on Saturday that the 25-year-old man had also been arrested on suspicion of murdering Mr Saleem, who was stabbed as he walked home from a mosque in Small Heath, Birmingham, in April.
In a statement, Ms May said: "I have been shocked and sickened at the brutal murder of Mohammed Saleem and recent attacks on mosques in the West Midlands, all of which are now being investigated as terrorist incidents. The West Midlands Police have my full support in their on-going investigation. I have spoken with Assistant Chief Constable Marcus Beale and I have asked that I am kept up-to-date with the latest developments.
"The Security Minister James Brokenshire will also be visiting Birmingham on Tuesday to meet those who have been directly affected. What happened in the West Midlands is a reminder that terrorism affects people of all backgrounds. Just as we saw people coming together to denounce Woolwich, so we must come together and stand firm against extremism whatever form it takes."
West Midlands Police said the older suspect was arrested at 5.05pm on Saturday in relation to "a further act of terrorism". A police spokesman said: "This arrest is in connection with the murder of Mohammed Saleem in Small Heath, Birmingham on Monday April 29." The Ukrainian nationals were detained in Small Heath shortly before 3pm on Thursday by detectives investigating explosions in the Caldmore area of Walsall on June 22, and in Tipton, near Dudley, on July 12.
Mr Saleem died after suffering three stab wounds to his back in Little Green Lane.
Following the men's arrest the "seat of an explosion and debris" were found on a roundabout near the Wolverhampton Central Mosque. Police believe the debris came from a device that exploded on the city's Fiveways roundabout on June 28. No-one was injured by any of the explosions.