Westpac New Zealand is withdrawing pre-approvals for some mortgage customers with high loan-to-valuation ratios, joining Commonwealth Bank's ASB in a move to try to slow lending to meet a Reserve Bank speed limit that kicked in from October 1.A Westpac spokesman was quoted as telling the New Zealand Herald the bank was now contacting customers with pre-approvals "to ensure they have up to date interest rate and lending criteria information after recent market changes made in response to new Reserve Bank regulations on high LVR ratios".The spokesman said in some instances customers may be told the bank could not continue pre-approvals under the existing terms."Before we get to that there is a whole raft of products that we would look at to try and help them," the spokesman said.Meanwhile, a BNZ-REINZ survey of real estate agents in early October found a collapse in interest by first-home buyers. The percentage of agents saying there were more first-home buyers in the market slumped to negative 41 per cent from positive 24 per cent the previous month. "Almost all measures have registered substantial declines, including the proportion of agents noticing more first-home buyers in the market," said BNZ economist Tony Alexander.