Two attacks on houses in Dunmurry on the outskirts of Belfast may have been "racially motivated", police have said.
Three windows were smashed at a house in Seymour Hill Mews and paint thrown at another in Rowan Drive on Sunday, Lithuanians live in both houses.
The attacks bring to six the number of suspected racially motivated incidents in Northern Ireland over the weekend.
There has been widespread condemnation of the attacks. In one incident three women were beaten with baseball bats.
Five masked men, armed with baseball bats, forced their way into their home at Cloughey, County Down at about 2330 BST on Saturday.
They suffered cuts, bruises and minor head injuries.
The Secretary of State, Peter Hain, has condemned the weekend attacks.
Mr Hain called on community representatives to form a united front to help police stamp out such attacks.
On Monday, Pastor Stanley McMahon from the Ards Intra Cultural Forum said incidents like this were making migrant workers feel "very unwelcome".
"These attacks do highlight a problem while they are very wrong, and callous and cowardly they are sending out a message of fear to the immigrant people saying 'we don't want you here'," he said.
"While we must always condemn all of these attacks we must go beyond that and assure the people that we don't want to sent this message out to them."
Anti-racist campaigner Doreen Lawrence, who is speaking at a conference in Belfast on Monday, said more needed to be done to tackle the problem.
"I'm trying to get my head round or understand what is happening here," she said.
"Why there is so much, why the increase is happening and what the government is trying to do about it."
Mrs Lawrence, mother of murdered black teenager Stephen Lawrence, was in the city for the launch of a new report on racist violence in the province.
Police are also investigating an arson attack in Carrickfergus at 0800 BST on Sunday.
The back of the house at Burleigh Drive was extensively damaged after an oil tank caught fire.
It is believed the people who live in the house are Polish nationals. No-one was injured in the incident.
On Saturday, a Latvian man was attacked by two men with bats and sticks on the Moira Road in Lisburn.
A 24-year-old man has been charged with assault, aggravated burglary, criminal damage and possessing an offensive weapon in relation to the assault.
He is to appear at Lisburn Magistrates Court on Monday.
Another man, also aged 24, has been arrested in connection with the assault.
Meanwhile, a man arrested in connection with an attack in Castledawson has been released on police bail.
The victim, who is understood to be Lithuanian, was assaulted at a house in Riverside South on Sunday.