Copper prices came under pressure on Tuesday as demand concerns resurfaced after weak manufacturing data from top consumer China spurred selling, while a softer dollar provided some support.

Benchmark copper on the London Metal Exchange (LME) was little changed at $8,135 a metric ton at 1213 GMT after falling as far as $8,089 a ton.

It hit a four-week high of $8,231 on Monday due to recent signs of economic stabilisation in China. Copper prices are on course for their third monthly decline.

However, China's manufacturing sector unexpectedly shrank in October, underlined the daunting task facing policymakers as they try to revitalise economic growth heading into the end of the year and 2024.

Both new export and import orders contracted for an eighth consecutive month, suggesting that manufacturers were struggling to find buyers overseas and ordering fewer components used in finished goods for re-export.

"The main driver for base metals is still China demand," said Dan Smith, head of research at Amalgamated Metal Trading, adding that fresh China stimulus announced last week had helped boost metals prices.

China last week approved one trillion-yuan ($137 billion) in sovereign bond issuance and passed a bill allowing local governments to front-load part of their 2024 bond quotas to support investment.

"Today's data show the growth struggle of China. Monetary tools aren't working and traditional fiscal tools have reached their limits," said Sandeep Daga, a director at analysis company Metal Intelligence Centre.

Traders said falling stocks of copper in LME approved warehouses , those monitored by the Shanghai Futures Exchange and in CME registered warehouses were helping sentiment.

They are also awaiting a decision on U.S. rates from the Federal Reserve on Wednesday which could influence dollar direction.

A lower U.S. currency potentially helps bolster demand for dollar-priced base metals for holders of other currencies.

Aluminium slipped 0.3% to $2,258, zinc fell 0.9% to $2,444, lead ceded 0.3% to $2,115, tin was down 0.8% at $24,805 and nickel retreated 1.2% to $18,260 a ton.

(Reporting by Julian Luk; additional reporting by Mai Nguyen; editing by Kirsten Donovan)