Colin Ross, 53, has been missing for a week.

A family friend has paid for a private helicopter to search for missing Marlborough man Colin Ross.

The 53-year-old was last seen in Blenheim, near the fire station, about 5pm on October 25.

Family friend Angelina Yve Grace said her father, John Young, had paid for a private helicopter to search for Ross on Wednesday afternoon.

SUPPLIED Colin Ross may be driving his 1996 Toyota Rav 4, like the one in this photograph. Registration AJY 133.

Ross lived in the Waihopai Valley, about 30 kilometres southwest of Blenheim.

"They're going to go to his usual spots where he goes walking towards the end of Waihopai Valley," Yve Grace said.

Police said Ross could be in a red or maroon-coloured 1996 Toyota RAV 4, with the number plate AJY 133.

The vehicle was also last seen in the Blenheim town centre on October 25 about 5pm.

Police said they had not started a physical search for Ross, but they were asking for information on his whereabouts.

Police said they were concerned for his safety.

Yve Grace said Ross's disappearance was completely out of character.

"I've been really upset, he's quite an outdoors person . . . it's not like him to leave his phone behind unless he's going for a walk where there is no phone reception.

"He was the life of the party, always helping somebody and always someone you can rely on," Yve Grace said.

Yve Grace said the family welcomed donations to help cover the cost of the search.

Anyone with information should contact Blenheim police on 03 578 5279.

Alternatively, anonymous tips can be passed on to Crimestoppers on 0800 555 111.