* Brazilian police visited offices as part of corruption probe
* Shares plunge, despite Arcadis's limited exposure to Brazil (Adds analyst explanation for share price fall)
AMSTERDAM, Dec 14 (Reuters) - Dutch engineering firm Arcadis said on Monday it was cooperating with Brazilian police as part of an investigation into suspected misuse of funds at a $6.4 billion water management project in northern Brazil.
Arcadis, which has water management and mining industry contracts in Brazil, did not specify whether it may also be targeted in the investigation into the São Francisco project.
"We are also not clear on that," spokesman Joost Slooten said. The company acts as manager for the project in a 50/50 joint venture with Brazil's Concremat.
Arcadis's shares were down 19 percent at 17.01 euros at 1135 GMT, with investors apparently spooked by memories of the Brazilian corruption probes that have dogged marine engineer SBM Offshore for years, said ESN/SNS Securities Analyst Edwin Jong.
"The share reaction is overdone," he said. "Brazil is only 5 percent of Arcadis's business."
SBM Offshore, which paid a record $240 million to Dutch prosecutors to settle allegations of bribery, made 60 percent of its sales in the country.
Work to divert the São Francisco, Brazil's second-longest river, to the country's drought-prone northwest has been under way since 2006, and the estimated cost has nearly doubled.
Brazilian police arrested four people on Friday, saying they had evidence companies involved in the long-delayed project had used shell companies to divert funds.
Slooten said no Arcadis workers were arrested on Friday. The company said in a statement federal authorities visited Arcadis offices in São Paulo and the home of one of its managers.
Police asked for and were given documentation, he said, adding the company would continue to cooperate with authorities and had opened its own internal assessment of the situation.
The company warned in July a slowdown in procurement by the Brazilian government would lead to a decline of up to 30 percent in Arcadis's revenue in Brazil. It does not break out separate figures for Brazil.
In October, it repeated that annual revenue for the company as a whole would grow by about 30 percent and profits by 20 percent in 2015, despite the slowdown in Brazil. (Reporting by Toby Sterling and Thomas Escritt; Editing by Susan Thomas and Keith Weir)