Coffee chain Starbucks is asking US customers to leave their guns at home after the company was dragged into the increasingly divisive debate over the country's gun laws.

While many US restaurant chains and retailers do not allow firearms on their properties, Starbucks' policy had been to default to local gun laws, including "open carry" regulations in many US states that allow people to bring guns into stores.

In August, this led gun-rights advocates to hold a national "Starbucks Appreciation Day" to thank the firm for its stance, pulling the company deeper into the fierce political fight.

Events were planned for the store in Newtown, Connecticut, where 20 children and six adults were shot dead in an elementary school in December.

The shop was closed before the event was scheduled to begin.

In an open letter to customers, Starbucks chief executive Howard Schultz said the Appreciation Day events "disingenuously [portrayed] Starbucks as a champion of 'open carry'."

We are respectfully requesting that customers not bring weapons into our stores. Here’s why: bit.ly/1eNZ0ci — Starbucks News (@Starbucksnews) September 18, 2013

"To be clear: we do not want these events in our stores," the statement read.

The coffee chain did not, however, issue an outright ban on guns in its nearly 7,000 company-owned cafes, saying this would potentially require staff to confront armed customers.

The Seattle-based company hoped to give "responsible gun owners a chance to respect its request," Mr Schultz said.

The CEO told Reuters the policy change was not the result of the Newtown Starbucks Appreciation Day event, which prompted the Newtown Action Alliance to call on the company to ban guns at all of its US stores.

Nor was it in response to the mass shooting this week at the Washington Navy Yard.

Mr Schultz said the debate about open carry laws had become "increasingly uncivil ... even threatening".

"Some anti-gun activists have also played a role in ratcheting up the rhetoric and friction, at times soliciting and confronting employees and patrons," he said in the statement.

"We found ourselves in a position where advocates on both sides of the issue were using Starbucks as a staging ground for their own political position."

Mr Schultz said more people had been bringing guns into Starbucks shops over the last six months, prompting confusion and dismay among some customers and employees.

"I'm not worried we're going to lose customers over this," he said.

"I feel like I've made the best decision in the interest of our company."

Starbucks says the request does not extend to authorised law enforcement personnel.

Reuters