In their letters, first reported by Dutch daily Het Financieele Dagblad on Friday, the managers said ABN could become a takeover target, and that Chief Executive Kees van Dijkhuizen was not showing strong leadership.

"I understand that change can cause concern, but I do not share these concerns", Van Dijkhuizen said in a memo sent to ABN staff on Friday, seen by Reuters.

State-backed ABN Amro went through some management upheaval earlier this year. Chairwoman Olga Zoutendijk stepped down after internal issues over her "leadership style."

Since taking over as CEO in 2017, Van Dijkhuizen pruned the top layers of the bank, cutting the number of managers.

"Some people are disappointed, did not get the job they wanted," Van Dijkhuisen wrote in the memo. "But I can see that trust and calm are coming back."

ABN Amro, one of the Netherlands' three biggest banks, was nationalised during the 2008 financial crisis and returned to the Amsterdam stock exchange in 2015. The Dutch government still holds 56 percent.

Since its bailout ABN does about 80 percent of its business in the Netherlands. Its international operations focus largely on serving Dutch clients abroad.

Van Dijkhuizen last year said he would seek modest growth in international lending, focusing on commodities, renewable energy, food supply chain and utility providers.

But the managers said the strategy lacked clarity in their letters directed to the Dutch central bank, financial markets authority and Finance ministry.

The regulatory bodies declined comment.

"We had preferred it if the managers had directed their grievances directly at Kees [van Dijkhuizen]", ABN spokesman Jarco de Swart said. "Then they could have seen that their concerns were already dealt with. Important steps have been taken in recent months."

Finance Minister Wopke Hoekstra on Friday expressed his confidence in ABN's board and told reporters he was "very pleased" with the announcement of former Chief Financial Officer Tom de Swaan as the bank's new chairman last week.

(Reporting by Bart Meijer. Editing by Jane Merriman)

By Bart H. Meijer