BAGHDAD (UPI) -- Iraq's Kurdish leaders are quietly pushing ahead with a new constitution alarming some Iraqi and U.S. officials, observers say.

The move is seen by some as a threat to the country's unity.

The new constitution, scheduled for a referendum this year, underscores the level of mistrust and bad faith between the region and the central government in Baghdad, The New York Times says.

The proposed constitution backs Kurdish claims to territories and the oil and gas beneath them, claims that are disputed by both the Baghdad government and ethnic groups.

While these claims supposedly were being discussed, the Kurdish parliament pushed through the constitution. The Times said it was partly a message that it would resist pressure from the American and Iraqi governments to make concessions.

Meanwhile, the Obama administration, which is gradually withdrawing American troops from Iraq, appeared surprised and troubled by the Kurdish move.