A day before a runoff US Senate election and as Donald Trump prepared to visit the state to stage two rallies, nooses and six signs were found on the grounds of the Mississippi capitol.

Chuck McIntosh, a spokesman for the state department of finance and administration, which oversees the capitol, said the nooses and signs were found on Monday shortly before 8am, on the south side of the grounds.

The matter was under investigation, he said, adding that he did not know what was on the signs. A local television station showed photos of the nooses hanging over tree limbs, and described the rest as “hate signs”.

BREAKING: Nooses, hate signs found at Mississippi State Capitol https://t.co/lSIHPD0kDO pic.twitter.com/Phg7vlfV71 — WLBT 3 On Your Side (@WLBT) November 26, 2018

Later on Monday, investigators said that the handwritten signs referred to the state’s history of lynchings and to the forthcoming election.

The Senate runoff on Tuesday is between the Republican senator Cindy Hyde-Smith and Democrat Mike Espy, in a race that has increasingly taken on racial overtones.

In a public comment earlier this month, Hyde-Smith referred enthusiastically to “a public hanging”, a remark which immediately caused controversy in a state where racially motivated lynchings were common. She has also been linked to Confederate imagery and favourable expressions about Confederate troops and leaders.

Espy would be the first African American senator from Mississippi since the Reconstruction era, after the civil war and the abolition of slavery.

Trump was due to host two events in support of Hyde-Smith on Monday.