Updated

The government's ban on liquids and gels in airliner passenger cabins is confusing travelers. Further complicating matters is a carry-on ban on some trans-Atlantic flights.

The restrictions are part of tighter airline security ordered by the U.S. and British governments in the wake of a foiled terror plot involving liquid explosives.

The new policies aren't always clear or consistent.

For example, carry-on baggage — including most purses and laptop computers — is banned on all flights from Britain and on some flights from the U.S. to Britain. British Airways bans carry-on baggage from the U.S. to the U.K., but U.S. airlines do not.

British authorities require passengers to taste baby formula or milk at checkpoints, but U.S. officials only want to look at it.

Carry-on bags and electronic equipment are allowed on domestic flights.

It is unclear whether some items, such as liquid eyeliner, are considered to be a liquid or gel. The Transportation Security Administration advises travelers to check such items.

"Leave the Chanel and the high-priced stuff in checked baggage," said British Airways spokesman John Lampl.

Laptops, iPods and cell phones are banned from the passenger cabin on all flights to the U.S. from Britain and on British Airways flights from the U.S. to the U.K. Travelers can carry a crossword puzzle that fits into a pocket, plus a pencil or pen. But newspapers will not be allowed, Lampl said.

To help security officials move people through security as quickly as possible, TSA chief Kip Hawley offers some simple advice: "Declutter your bag."

Since announcing what's allowed in passenger cabins, the TSA has clarified some of its policies, which apply to domestic flights.

Liquids or gels not allowed in passenger cabins:

— Beverages

— Shampoo

— Suntan lotion

— Creams

— Toothpaste

— Hair gel

The TSA permits:

— Baby formula, which must be presented for inspection at the checkpoint

— Prescription medicines that match the passenger's name

— Essential nonprescription medicines, such as insulin

— Food, unless it has a gel-like consistency

— Electronic items such as laptops, CD players and iPods; British Airways flights to Britain do not allow them.

British Airways PLC, the largest carrier between Britain and the United States, offers these guidelines for carry-on items.

Allowed in the cabins:

— Pocket-size wallets and pocket-size purses, such as money, credit cards and identity cards

— Travel documents essential for the journey such as passports and tickets

— Prescription medicines and medical items sufficient and essential for the flight (for example, a diabetic kit), except in liquid form unless verified as authentic

— Spectacles and sunglasses, without cases

— Contact lens holders, without bottles of solution

— Female sanitary items sufficient and essential for the flight, if unboxed, including tampons, pads, towels and wipes

— Unboxed tissues and handkerchiefs

— Keys, but no electrical key fobs.

For those carrying an infant on a British Airways flight, the following are allowed:

— Baby food and milk, but the contents of each bottle must be tasted by the accompanying passenger

— Sanitary items sufficient and essential for the flight, such as diapers, wipes, creams and diaper disposal bags.

Not allowed:

— Handbags

— Cosmetics, including lipstick

— All electronic items

— Newspapers (British Airways has them on board for passengers)