Google has apologised for offence caused by vandalism of its Maps tools that meant that users searching for racist terms are being sent White House.

In what appears to be a result of Google bombing — where vandals flood a certain keyword with links to a place, meaning that the two will become associated in Google's results — users forced searches for "nigger house" and "nigger king" to redirect to the White House.

The search still has the same results, at least two days after it was first noticed.

The company said that it apologised for "any offence this may have caused". Its teams are working to fix the problem, it said, and Google itself does not appear to have had any role in adding the racist searches.

Google's mapping tools pick through the huge amounts of search data that it has to help ensure that results are up to date. But by intentionally confusing that system, users can add their own results.

Users can also set up businesses and then change the address so that they will show up wherever they want. It's unclear whether either of those workarounds were used to plant the White House results, or whether it was done using other means.